Control of octahedral rotations and physical properties in srruo3 perovskite oxide films

CONTROL OF OCTAHEDRAL ROTATIONS AND PHYSICAL PROPERTIES IN SRRUO3 PEROVSKITE OXIDE FILMS LU WENLAI (B. E., SHANGHAI JIAOTONG UNIVERSITY, CHINA) A THESIS SUBMITTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY DEPARTMENT OF MATERIALS SCIENCE AND ENGINEERING NATIONAL UNIVERSITY OF SINGAPORE 2014 DECLARATION I hereby declare that this thesis is my original work and it has been written by me in its entirety. I have duly acknowledged all the sources of information which have been used in the thesis. This thesis has also not been submitted for any degree in any university previously. Lu Wenlai __________________ LU WENLAI January 2014 Acknowledgements ACKNOWLEDGEMENTS My deepest gratitude goes first to my supervisors, Prof. Chen Jingsheng, Prof. Chow Gan Moog and Dr. Song Wendong for their invaluable advice and encouragement throughout my PhD study. Their creative ideas and inspiring suggestions make my PhD experience both rich and stimulating. I greatly appreciate the kind help from Dr. Yang Ping about my work regarding the synchrotron x-ray diffraction performed at Singapore Synchrotron Light Source (SSLS). I wish to thank Dr. He Kaihua for his help in conducting the first-principles calculations in the first part of my Ph.D. studies. I would like to thank the Advanced Photon Source (APS) at Argonne National Laboratory for their help in my XAFS measurement. Particularly, I would like to express my grateful appreciation to Dr. Sun Cheng-Jun for performing the measurements and processing the results so promptly. Moreover, I am greatly indebted to the entire team of lab technologies in the Advanced Materials Characterization Laboratory in my department for their assistance and facility training, without which my work cannot be completed. In addition, I would like to offer my deep gratitude to the financial support provided by the National University of Singapore Research Scholarship. I thank all my labmates for their support and encouragement: Dr. Jiang Changjun, Dr. Si Huayan, Dr. He Kaihua, Dr. Dong Kaifeng, Dr. Huang Lisen, i Acknowledgements Dr. Li Huihui, Dr. Xu Dongbin, Dr. Ho Pin, Dr. Guo Rui, Zhang Bangmin and Parvaneh. In particular, I wish to give thanks to my close friends: Tang Chunhua, Dr. Huang Xuelian, Dr. Neo Chinyong and Sherlyn. Last but not least, I wish to give my deepest thanks to my family for their care, support and love at every stage of my life. ii Table of Contents TABLE OF CONTENTS Acknowledgements . i Table of Contents . iii Summary .vii List of Tables . x List of Figures xi CHAPTER Introduction 1.1 Perovskite Materials . 1.1.1 Crystal Structure 1.1.2 Physical Properties and Applications 1.2 Octahedral Rotations 1.2.1 Description of Octahedral Rotations - Glazer Tilt System 10 1.2.2 Important Role of Octahedral Rotations . 13 1.2.3 Strain Engineering of Physical Properties . 15 1.2.4 Determination of Octahedral Rotations . 18 1.3 SrRuO3 Thin Films . 19 1.3.1 Structure of bulk SRO and thin film SRO . 21 1.3.2 Magnetic Properties . 24 1.3.3 Electrical Transport Properties 25 1.4 Objectives and Significance . 26 CHAPTER Experimental . 30 2.1 Film Deposition-Pulsed Laser Deposition (PLD) 30 2.2 X-ray Diffraction (XRD) 32 2.2.1  - 2 scan . 33 2.2.2 Reciprocal Space Mapping (RSM) . 33 2.2.3 Half-integer reflections using synchrotron x-rays . 36 iii Table of Contents 2.3 X-ray Photoelectron Spectroscopy (XPS) 40 2.4 X-ray Absorption Spectroscopy (XAS) . 41 2.5 Superconducting Quantum Interference Device (SQUID) 42 2.6 Physical Property Measurement System (PPMS) 43 2.7 First-principles Calculations 43 CHAPTER The Role of Oxygen Vacancy on the Structural Phase Transition and Physical Properties in SrRuO3 Films . 45 3.1 Introduction 45 3.2 Experimental 46 3.3 Results and Discussion . 46 3.3.1 Stoichiometry and Morphology 46 3.3.2 Structural Properties and Phase Transition 48 3.3.3 Origin of the Structural Phase Transition 56 3.3.4 Magnetic Properties . 61 3.3.5 Electrical Transport Properties and Electronic Structure 67 3.4 Summary 76 CHAPTER Control of Octahedral Rotations and Physical Properties in SrRuO3 Films by Varying Oxygen Content and Film Thickness 79 4.1 Introduction 79 4.2 Experimental 80 4.3 Results and Discussion . 81 4.3.1 Crystal Structures 81 4.3.2 Identification of Octahedral Rotations 82 4.3.3 Control of Octahedral Rotations . 87 4.3.4 Control of Physical Properties 93 4.4 Summary 101 CHAPTER Control of Octahedral Rotations and Physical Properties in SrRuO3 Films by Strain Engineering . 104 iv Table of Contents 5.1 Introduction 104 5.2 Experimental Design 105 5.2.1 The Effect of Misfit Strain 106 5.2.2 The Effect of Octahedral Rotation Pattern of Substrate 108 5.3 Results and Discussion . 111 5.3.1 SRO film on KTO Substrate . 112 5.3.2 SRO film on STO Substrate 118 5.3.3 SRO film on NGO Substrate . 118 5.3.4 SRO film on LAO Substrate . 124 5.3.5 SRO film on NCAO Substrate 129 5.4 Discussion and Conclusion 133 CHAPTER Conclusions and Future Research 137 Bibliography . 144 Appendices 157 List of Publications 157 v Table of Contents vi Chapter account. Secondly, this work was limited to the material SRO while other perovskite materials were not considered. This is because SRO is an ideal representative perovskite material to study the relationship between octahedral rotations and physical properties since the electrical and magnetic property of this material is intimately tied to the electrons lying in a band formed by the overlap between Ru 4d orbital and O 2p orbital. A subtle change in the octahedra (formed by Ru and O atoms) would result in substantial changes in the electronic structure, which affect in a significant way its electrical and magnetic properties. Finally we outline some on-going and new research directions based on this study. i) Not only the rotation pattern, but also the size, shape of the octahedra is crucial to engineering material properties in perovskites. Therefore, one possible avenue for future work is to study how to modify the physical properties through crystal field splitting by tailoring the size and shape of the octahedra, as found in many copper (II) complexes. ii) Another interesting area for future work is to use a variety of external stimuli, especially the external electrical fields,150 to manipulate the octahedral rotations and thus the multi-functionality of the perovskite materials. The tuning of the octahedral rotations could be utilized to position the perovskites closer to functional phase boundaries where the 142 Chapter external electrical fields may be used to traverse and induce colossal responses, and thus could be applied to low-power electronic devices.151 iii)It should be pointed out that, with the rapid development in the field of multiferroics, there is currently a significant renewed interest in the competition between octahedral tilts and cation displacements. BiFeO3 is an exciting example for it is the only pure perovskite presenting strong tilts and cation displacements at room temperature.53 Further research is therefore needed to study the coupling between octahedral rotations and cation displacements which should offer high potential in future applications. In summary, this study provides several emerging and effective pathways to control over octahedral rotations as well as a comprehensive understanding of how the physical properties in SrRuO3 films are coupled to the geometric patterns of the corner-shared octahedra. This control of octahedral rotations is promising for discovering and designing multifunctional phases in perovskite oxides. 143 Bibliography BIBLIOGRAPHY 1. Goodenough, J. B. "Electronic and ionic transport properties and other physical aspects of perovskites". Rep. Prog. Phys. Vol. 67, No. 11, 1915-1993 (2004). 2. Salamon, M. B. & Jaime, M. "The physics of manganites: Structure and transport". Rev. Mod. Phys. Vol. 73, No. 3, 583-628 (2001). 3. Imada, M., Fujimori, A. & Tokura, Y. "Metal-insulator transitions". Rev. Mod. Phys. Vol. 70, No. 4, 1039-1263 (1998). 4. Martin, L. W., Chu, Y. H. & Ramesh, R. "Advances in the growth and characterization of magnetic, ferroelectric, and multiferroic oxide thin films". Materials Science and Engineering: R: Reports Vol. 68, No. 4–6, 89-133 (2010). 5. Chen, Z. et al. "Coexistence of ferroelectric triclinic phases in highly strained BiFeO3 films". Phys. Rev. B Vol. 84, No. 9, 094116 (2011). 6. Haeni, J. H. et al. "Room-temperature ferroelectricity in strained SrTiO3". Nature Vol. 430, No. 7001, 758-761 (2004). 7. Liu, H. et al. "Uniaxial strain-induced ferroelectric phase with a giant axial ratio in a (110) BiFeO3 thin film". Phys. Rev. B Vol. 87, No. 22, 220101 (2013). 8. Liu, H. et al. "Origin of a Tetragonal BiFeO3 Phase with a Giant c/a Ratio on SrTiO3 Substrates". Adv. Funct. Mater. Vol. 22, No. 5, 937-942 (2012). 9. Luo, W., Pennycook, S. J. & Pantelides, S. T. "Magnetic “Dead” Layer at a Complex Oxide Interface". Phys. Rev. Lett. Vol. 101, No. 24, 247204 (2008). 10. Ramesh, R. & Schlom, D. G. "Whither Oxide Electronics?". MRS Bull. Vol. 33, No. 11, 1006-1014 (2008). 11. Schlom, D. G. et al. "Strain Tuning of Ferroelectric Thin Films*". Annu. Rev. Mater. Res. Vol. 37, No. 1, 589-626 (2007). 144 Bibliography 12. Streiffer, S. K. & Fong, D. D. "Phase transitions in nanoscale ferroelectric structures". MRS Bull. Vol. 34, No. 11, 832-837 (2009). 13. Zeches, R. J. et al. "A strain-driven morphotropic phase boundary in BiFeO3". Science Vol. 326, No. 5955, 977-980 (2009). 14. He, J., Borisevich, A., Kalinin, S. V., Pennycook, S. J. & Pantelides, S. T. "Control of Octahedral Tilts and Magnetic Properties of Perovskite Oxide Heterostructures by Substrate Symmetry". Phys. Rev. Lett. Vol. 105, No. 227203 (2010). 15. "Perovskite (Structure)". http://en.wikipedia.org/wiki/Perovskite_(structure) 16. Imai, T., Sasaura, M., Nakamura, K. & Fujiura, K. "Crystal Growth and Electro-optic Properties of KTa1-xNbxO3". Ntt Technical Review Vol. 5, No. 9, (2007). 17. Megaw, H. D. Ferroelectricity in Crystals. Methuen, London (1957). 18. Megaw, H. D. Crystal structures: a working approach. Saunders, Philadelphia (1973). 19. Glazer, A. M. "The classification of tilted octahedra in perovskites". Acta Crystallogr. B Vol. 28, No. 11, 3384-3392 (1972). 20. Millis, A. J., Littlewood, P. B. & Shraiman, B. I. "Double Exchange Alone Does Not Explain the Resistivity of La1-xSrxMnO3". Phys. Rev. Lett. Vol. 74, No. 25, 5144-5147 (1995). 21. Inoue, I. H., Goto, O., Makino, H., Hussey, N. E. & Ishikawa, M. "Bandwidth control in a perovskite-type 3d1-correlated metal Ca1-xSrxVO3. I. Evolution of the electronic properties and effective mass". Phys. Rev. B Vol. 58, No. 8, 4372-4383 (1998). 22. Goldschmidt, V. M. "The laws of crystal chemistry". Naturwissenschaften Vol. 14, No. 477-485 (1926). 23. Li, C., Soh, K. C. K. & Wu, P. "Formability of ABO3 perovskites". J. Alloy. Compd. Vol. 372, No. 1-2, 40-48 (2004). 145 Bibliography 24. "Distortion of Perovskites". http://www.ccp14.ac.uk/ccp/web-mirrors/pki/uni/pki/members/schinzer/st ru_chem/perov/di_gold.html 25. Ruddlesden, S. N. & Popper, P. "The compound Sr3Ti2O7 and its structure". Acta Crystallographica Vol. 11, No. 1, 54-55 (1958). 26. Wu, M. K. et al. "Superconductivity at 93 K in a new mixed-phase Y-B-Cu-O compound system at ambient pressure". Phys. Rev. Lett. Vol. 58, No. 9, 908-910 (1987). 27. Scott, J. F. & Paz de Araujo, C. A. "Ferroelectric Memories". Science Vol. 246, No. 4936, 1400-1405 (1989). 28. Wang, J. et al. "Epitaxial BiFeO3 Multiferroic Thin Film Heterostructures". Science Vol. 299, No. 5613, 1719-1722 (2003). 29. Van Aken, B. B., Palstra, T. T. M., Filippetti, A. & Spaldin, N. A. "The origin of ferroelectricity in magnetoelectric YMnO3". Nat. Mater. Vol. 3, No. 3, 164-170 (2004). 30. Kimura, T. et al. "Magnetic control of ferroelectric polarization". Nature Vol. 426, No. 6962, 55-58 (2003). 31. Ramirez, A. P. "Colossal magnetoresistance". J. Phys-condens. Mat. Vol. 9, No. 39, 8171-8199 (1997). 32. Tokura, Y. & Tomioka, Y. "Colossal magnetoresistive manganites". J. Magn. Magn. Mater. Vol. 200, No. 1–3, 1-23 (1999). 33. Rao, C. N. R. & Cheetham, A. K. "Charge Ordering in Manganates". Science Vol. 276, No. 5314, 911-912 (1997). 34. Attfield, J. P. "Charge ordering in transition metal oxides". Solid State Sci. Vol. 8, No. 8, 861-867 (2006). 35. Maeno, Y. et al. "Superconductivity in a layered perovskite without copper". Nature Vol. 372, No. 6506, 532-534 (1994). 36. Johnsson, M. & Lemmens, P. "Perovskites and thin films - crystallography and chemistry". J. Phys-condens. Mat. Vol. 20, No. 26, (2008). 146 Bibliography 37. Wul, B. & Goldman, J. M., C. R. Acad. Sci. URSS Vol. 46, No. 139 (1945). 38. Shirane, G. & Takeda, A. "Phase transitions in solid solutions of PbZrO3 and PbTiO3 (I) small concentrations of PbTiO3". J. Phys. Soc. Jpn. Vol. 7, No. 1, (1952). 39. Sawaguchi, E. "Ferroelectricity versus antiferroelectricity in the solid solutions of PbZrO3 and PbTiO3". J. Phys. Soc. Jpn. Vol. 8, No. 5, 615 (1953). 40. Jaffe, B., Roth, R. S. & Marzullo, S. "Piezoelectric properties of lead zirconate‐lead titanate solid‐solution ceramics". J. Appl. Phys. Vol. 25, No. 6, 809-810 (1954). 41. Cross, E. "Materials science: lead-free at last". Nature Vol. 432, No. 7013, 24-25 (2004). 42. Maeder, M. D., Damjanovic, D. & Setter, N. "Lead free piezoelectric materials". J. Electroceram. Vol. 13, No. 1-3, 385-392 (2004). 43. Saito, Y. et al. "Lead-free piezoceramics". Nature Vol. 432, No. 7013, 84-87 (2004). 44. Coey, J. M. D., Viret, M. & von Molnár, S. "Mixed-valence manganites". Adv. Phys. Vol. 58, No. 6, 571-697 (2009). 45. Dagotto, E., Hotta, T. & Moreo, A. "Colossal magnetoresistant materials: the key role of phase separation". Physics Reports Vol. 344, No. 1–3, 1-153 (2001). 46. Bednorz, J. G. & Müller, K. A. "Possible high Tc superconductivity in the Ba−La−Cu−O system". Zeitschrift für Physik B Vol. 64, No. 2, 189-193 (1986). 47. Hazen, R. M. et al. "Crystallographic description of phases in the Y-Ba-Cu-O superconductor". Phys. Rev. B Vol. 35, No. 13, 7238-7241 (1987). 48. Khare, N. Handbook of High-Temperature Superconductor. Taylor & Francis (2003). 147 Bibliography 49. Woodward, P. M. "Octahedral tilting in perovskites. I. Geometrical considerations". Acta Crystallogr. B Vol. 53, No. 32-43 (1997). 50. Mitchell, R. H. Perovskites: Modern and Ancient. Almaz Press Incorporated (2002). 51. Hatt, A. J., Spaldin, N. A. & Ederer, C. "Strain-induced isosymmetric phase transition in BiFeO3". Phys. Rev. B Vol. 81, No. 5, 054109 (2010). 52. Lebeugle, D. et al. "Room-temperature coexistence of large electric polarization and magnetic order in BiFeO3 single crystals". Phys. Rev. B Vol. 76, No. 2, (2007). 53. Kim, Y.-M. et al. "Interplay of octahedral tilts and polar order in BiFeO3 films". Adv. Mater. Vol. 25, No. 17, 2497-2504 (2013). 54. Akamatsu, H. et al. "Strong spin-lattice coupling through oxygen octahedral rotation in divalent europium perovskites". Adv. Funct. Mater. Vol. 23, No. 15, 1864-1872 (2013). 55. Bousquet, E. et al. "Improper ferroelectricity in perovskite oxide artificial superlattices". Nature Vol. 452, No. 7188, 732-736 (2008). 56. Rondinelli, J. M. & Fennie, C. J. "Octahedral rotation-induced ferroelectricity in cation ordered perovskites". Adv. Mater. Vol. 24, No. 15, 1961-1968 (2012). 57. Gopalan, V. & Litvin, D. B. "Rotation-reversal symmetries in crystals and handed structures". Nat. Mater. Vol. 10, No. 5, 376-381 (2011). 58. Benedek, N. A. & Fennie, C. J. "Hybrid Improper Ferroelectricity: A Mechanism for Controllable Polarization-Magnetization Coupling". Phys. Rev. Lett. Vol. 106, No. 10, 107204 (2011). 59. Choi, K. J. et al. "Enhancement of ferroelectricity in strained BaTiO3 thin films". Science Vol. 306, No. 5698, 1005-1009 (2004). 60. Kwon, C. et al. "Stress-induced effects in epitaxial (La0.7Sr0.3)MnO3 films". J. Magn. Magn. Mater. Vol. 172, No. 3, 229-236 (1997). 61. Suzuki, Y., Hwang, H. Y., Cheong, S. W. & vanDover, R. B. "The role of strain in magnetic anisotropy of manganite thin films". Appl. Phys. Lett. 148 Bibliography Vol. 71, No. 1, 140-142 (1997). 62. Grutter, A., Wong, F., Arenholz, E., Liberati, M. & Suzuki, Y. "Enhanced magnetization in epitaxial SrRuO3 thin films via substrate-induced strain". J. Appl. Phys. Vol. 107, No. 09E138 (2010). 63. Bohra, M. et al. "Role of Ru vacancies in the magnetism of strain relaxed SrRuO3 films on SrTiO3 substrates". J. Appl. Phys. Vol. 109, No. 7, (2011). 64. Grutter, A. J., Wong, F. J., Arenholz, E., Vailionis, A. & Suzuki, Y. "Evidence of high-spin Ru and universal magnetic anisotropy in SrRuO3 thin films". Phys. Rev. B Vol. 85, No. 134429 (2012). 65. Vailionis, A. et al. "Misfit strain accommodation in epitaxial ABO3 perovskites: Lattice rotations and lattice modulations". Phys. Rev. B Vol. 83, No. 6, 064101 (2011). 66. Chang, S. H. et al. "Thickness-dependent structural phase transition of strained SrRuO3 ultrathin films: The role of octahedral tilt". Phys. Rev. B Vol. 84, No. 10, 104101 (2011). 67. Glazer, A. M. "Simple ways of determining perovskite structures". Acta Crystallogr. A Vol. 31, No. 6, 756-762 (1975). 68. Ahtee, M. & Glazer, A. M. "Lattice-parameters and tilted octahedra in sodium-potassium niobate solid-solutions". Acta Crystallogr. A Vol. 32, No. 3, 434-446 (1976). 69. Ahtee, A., Ahtee, M., Glazer, A. M. & Hewat, A. W. "The Structure of orthorhombic SrZrO3 by neutron powder diffraction". Acta Crystallogr. B Vol. 32, No. 12, 3243-3246 (1976). 70. Ahtee, M. & Unonius, L. "The Structure of NaTaO3 by x-ray powder diffraction". Acta Crystallogr. A Vol. 33, No. 1, 150-154 (1977). 71. Hidaka, M. & Ono, M. "Crystal-structure of NaNiF3". J. Phys. Soc. Jpn. Vol. 43, No. 1, 258-263 (1977). 72. Khattak, C. P. & Cox, D. E. "Structural studies of (La,Sr)CrO3 system". Mater. Res. Bull. Vol. 12, No. 5, 463-471 (1977). 149 Bibliography 73. Souza-Neto, N. M., Ramos, A. Y., Tolentino, H. C. N., Favre-Nicolin, E. & Ranno, L. "Local tetragonal distortion in La0.7Sr0.3MnO3 strained thin films probed by x-ray absorption spectroscopy". Phys. Rev. B Vol. 70, No. 17, 174451 (2004). 74. Herger, R. et al. "Structure determination of monolayer-by-monolayer grown La1−xSrxMnO3 thin films and the onset of magnetoresistance". Phys. Rev. B Vol. 77, No. 8, 085401 (2008). 75. Borisevich, A. et al. "Mapping octahedral tilts and polarization across a domain wall in BiFeO3 from z-contrast scanning transmission electron microscopy image atomic column shape analysis". ACS Nano Vol. 4, No. 10, 6071-6079 (2010). 76. Jia, C. L. et al. "Oxygen octahedron reconstruction in the SrTiO3/LaAlO3 heterointerfaces investigated using aberration-corrected ultrahigh resolution transmission electron microscopy". Phys. Rev. B Vol. 79, No. 8, 081405 (2009). 77. Johnson-Wilke, R. L. et al. "Tilt transitions in compressively strained AgTa0.5Nb0.5O3 thin films". Phys. Rev. B Vol. 84, No. 13, 134114 (2011). 78. May, S. J. et al. "Quantifying octahedral rotations in strained perovskite oxide films". Phys. Rev. B Vol. 82, No. 1, 014110 (2010). 79. Muller, D. A. "Structure and bonding at the atomic scale by scanning transmission electron microscopy.". Nat. Mater. Vol. 8, 263-270 (2009). 80. Rotella, H. et al. "Octahedral tilting in strained LaVO3 thin films". Phys. Rev. B Vol. 85, No. 18, 184101 (2012). 81. Woodward, D. I. & Reaney, I. M. "Electron diffraction of tilted perovskites". Acta Crystallogr. B Vol. 61, No. 4, 387-399 (2005). 82. Randall, J. J. & Ward, R. "The preparation of some ternary oxides of the platinum metals1,2". J. Am. Chem. Soc. Vol. 81, No. 11, 2629-2631 (1959). 83. Cao, G., McCall, S., Shepard, M., Crow, J. E. & Guertin, R. P. "Thermal, magnetic, and transport properties of single-crystal Sr1-xCaxRuO3 (0 < ~ x < ~ 1.0)". Phys. Rev. B Vol. 56, No. 1, 321-329 (1997). 84. Eom, C. B. et al. "Single-crystal epitaxial thin films of the isotropic 150 Bibliography metallic oxides Sr1–xCaxRuO3 (0 ≤ x ≤ 1)". Science Vol. 258, No. 5089, 1766-1769 (1992). 85. Lee, H. N., Christen, H. M., Chisholm, M. F., Rouleau, C. M. & Lowndes, D. H. "Thermal stability of epitaxial SrRuO3 films as a function of oxygen pressure". Appl. Phys. Lett. Vol. 84, No. 20, 4107-4109 (2004). 86. Halley, D., Rossel, C., Widmer, D., Wolf, H. & Gariglio, S. "Thermal stability of SrRuO3 epitaxial layers under forming-gas anneal". Materials Science and Engineering: B Vol. 109, No. 1–3, 113-116 (2004). 87. Eom, C. B. et al. "Fabrication and properties of epitaxial ferroelectric heterostructures with (SrRuO3) isotropic metallic oxide electrodes". Appl. Phys. Lett. Vol. 63, No. 18, 2570-2572 (1993). 88. Prins, M. W. J. et al. "A ferroelectric transparent thin‐film transistor". Appl. Phys. Lett. Vol. 68, No. 25, 3650-3652 (1996). 89. Gruverman, A. et al. "Tunneling electroresistance effect in ferroelectric tunnel junctions at the nanoscale". Nano Letters Vol. 9, No. 10, 3539-3543 (2009). 90. Worledge, D. C. & Geballe, T. H. "Negative spin-polarization of SrRuO3". Phys. Rev. Lett. Vol. 85, No. 24, 5182-5185 (2000). 91. Herranz, G. et al. "SrRuO3/SrTiO3/SrRuO3 heterostructures for magnetic tunnel junctions". J. Appl. Phys. Vol. 93, No. 10, 8035-8037 (2003). 92. Rondinelli, J. M., Stengel, M. & Spaldin, N. A. "Carrier-mediated magnetoelectricity in complex oxide heterostructures". Nature Nanotech. Vol. 3, No. 1, 46-50 (2008). 93. Zhang, J. X., Dai, J. W., Chow, C. K., Sun, C. L. et al. "Magnetoelectric coupling in CoFe2O4∕SrRuO3∕Pb(Zr0.52Ti0.48)O3 heteroepitaxial thin film structure". Appl. Phys. Lett. Vol. 92, No. 2, 022901 (2008). 94. Niranjan, M. K., Burton, J. D., Velev, J. P., Jaswal, S. S. & Tsymbal, E. Y. "Magnetoelectric effect at the SrRuO3/BaTiO3 (001) interface: An ab initio study". Appl. Phys. Lett. Vol. 95, No. 5, 052501 (2009). 95. Han, T. C. & Lin, J. G. "Exchange bias between multiferroic HoMnO3 and 151 Bibliography ferromagnetic SrRuO3 films". J. Appl. Phys. Vol. 113, No. 17, 17D718 (2013). 96. Jones, C. W., Battle, P. D., Lightfoot, P. & Harrison, W. T. A. "The structure of SrRuO3 by time-of-flight neutron powder diffraction". Acta Crystallographica Section C Vol. 45, No. 3, 365-367 (1989). 97. Choi, K. J. et al. "Phase-transition temperatures of strained single-crystal SrRuO3 thin films". Adv. Mater. Vol. 22, No. 6, 759-762 (2010). 98. Kennedy, B. J. & Hunter, B. A. "High-temperature phases of SrRuO3". Phys. Rev. B Vol. 58, No. 2, 653-658 (1998). 99. Vailionis, A., Siemons, W. & Koster, G. "Room temperature epitaxial stabilization of a tetragonal phase in ARuO3 (A = Ca and Sr) thin films". Appl. Phys. Lett. Vol. 93, No. 5, 051909-051903 (2008). 100. Kan, D., Aso, R., Kurata, H. & Shimakawa, Y. "Thickness-dependent structure–property relationships in strained (110) SrRuO3 thin films". Adv. Funct. Mater. Vol. 23, No. 9, 1129-1136 (2013). 101. Gan, Q., Rao, R. a., Eom, C. B., Wu, L. & Tsui, F. "Lattice distortion and uniaxial magnetic anisotropy in single domain epitaxial (110) films of SrRuO3". J. Appl. Phys. Vol. 85, No. 8, 5297 (1999). 102. Jiang, J. C., Pan, X. Q. & Chen, C. L. "Microstructure of epitaxial SrRuO3 thin films on (001) SrTiO3". Appl. Phys. Lett. Vol. 72, No. 8, 909-911 (1998). 103. Koster, G. et al. "Structure, physical properties, and applications of SrRuO3 thin films". Rev. Mod. Phys. Vol. 84, No. 1, 253-298 (2012). 104.Kanbayasi, A. "Magnetic properties of SrRuO3 single crystal". J. Phys. Soc. Jpn. Vol. 41, No. 6, 1876 (1976). 105. Klein, L. et al. "Transport and magnetization in the badly metallic itinerant ferromagnet SrRuO3". J. Phys-condens. Mat. Vol. 8, No. 48, 10111-10126 (1996). 106. Kolesnik, S. et al. "Effect of crystalline quality and substitution on magnetic anisotropy of SrRuO3 thin films". J. Appl. Phys. Vol. 99, No. 8, 08F501 (2006). 152 Bibliography 107. Yoo, Y. Z. et al. "Diverse effects of two-dimensional and step flow growth mode induced microstructures on the magnetic anisotropies of SrRuO3 thin films". Appl. Phys. Lett. Vol. 89, No. 12, 124104 (2006). 108. Jung, C. U., Yamada, H., Kawasaki, M. & Tokura, Y. "Magnetic anisotropy control of SrRuO3 films by tunable epitaxial strain". Appl. Phys. Lett. Vol. 84, No. 14, 2590-2592 (2004). 109. Allen, P. et al. "Transport properties, thermodynamic properties, and electronic structure of SrRuO3.". Physical review. B, Condensed matter Vol. 53, No. 8, 4393-4398 (1996). 110. Herranz, G. et al. "Weak localization effects in some metallic perovskites". The European Physical Journal B Vol. 40, No. 4, 439-444 (2004). 111. Genish, I., Klein, L., Reiner, J. W. & Beasley, M. R. "Determination of the resistivity anisotropy of SrRuO3 by measuring the planar Hall effect". Phys. Rev. B Vol. 75, No. 12, 125108 (2007). 112. Genish, I., Kats, Y., Klein, L., Reiner, J. W. & Beasley, M. R. "Paramagnetic anisotropic magnetoresistance in thin films of SrRuO3". J. Appl. Phys. Vol. 95, No. 11, 6681-6683 (2004). 113. Rao, R. A., Kacedon, D. B. & Eom, C. B. "Anisotropic magnetotransport properties of epitaxial thin films of conductive ferromagnetic oxide SrRuO3". J. Appl. Phys. Vol. 83, No. 11, 6995-6997 (1998). 114. Ziese, M., Vrejoiu, I. & Hesse, D. "Structural symmetry and magnetocrystalline anisotropy of SrRuO3 films on SrTiO3". Phys. Rev. B Vol. 81, No. 18, 184418 (2010). 115. May, S. J. et al. "Control of octahedral rotations in (LaNiO3)n/(SrMnO3)m superlattices". Phys. Rev. B Vol. 83, No. 15, 153411 (2011). 116. Johnson-Wilke, R. L. et al. "Quantification of octahedral rotations in strained LaAlO3 films via synchrotron x-ray diffraction". Phys. Rev. B Vol. 88, No. 17, 174101 (2013). 117. Bunker, G. Introduction to XAFS: A Practical Guide to X-ray Absorption Fine Structure Spectroscopy. Cambridge University Press (2010). 118. Josephson, B. D. "The discovery of tunnelling supercurrents". Rev. Mod. 153 Bibliography Phys. Vol. 46, No. 2, 251-254 (1974). 119. Kresse, G. & Hafner, J. "Ab initio molecular dynamics for liquid metals". Phys. Rev. B Vol. 47, No. 1, 558-561 (1993). 120. Perdew, J. P., Burke, K. & Ernzerhof, M. "Generalized gradient approximation made simple". Phys. Rev. Lett. Vol. 77, No. 18, 3865-3868 (1996). 121. Vanderbilt, D. "Soft self-consistent pseudopotentials in a generalized eigenvalue formalism". Phys. Rev. B Vol. 41, No. 11, 7892-7895 (1990). 122. Monkhorst, H. J. & Pack, J. D. "Special points for Brillouin-zone integrations". Phys. Rev. B Vol. 13, No. 12, 5188-5192 (1976). 123. Siemons, W. et al. "Dependence of the electronic structure of SrRuO3 and its degree of correlation on cation off-stoichiometry". Phys. Rev. B Vol. 76, No. 7, 075126 (2007). 124. Chang, Y. J., Kim, J. I. & Jung, C. U. "Electrical properties of SrRuO3 thin films with varying c-axis lattice constant". Journal of Magnetics Vol. 13, No. 2, 61-64 (2008). 125. Moonshiram, D. et al. "Structure and electronic configurations of the intermediates of water oxidation in blue ruthenium dimer catalysis". J. Am. Chem. Soc. Vol. 134, No. 10, 4625-4636 (2012). 126. Zayak, A. T., Huang, X., Neaton, J. B. & Rabe, K. M. "Structural, electronic, and magnetic properties of SrRuO3 under epitaxial strain". Phys. Rev. B Vol. 74, No. 9, 094104 (2006). 127. Bune, R. O. et al. "Crystal structure and properties of Ru-stoichiometric LaSrMnRuO6". Chem. Mater. Vol. 18, No. 10, 2611-2617 (2006). 128. Herranz, G. et al. "Controlled magnetic anisotropy of SrRuO3 thin films grown on nominally exact SrTiO3(001) substrates". Appl. Phys. Lett. Vol. 89, No. 15, 152501 (2006). 129. Klein, L. et al. "Anomalous spin scattering effects in the badly metallic itinerant ferromagnet SrRuO3". Phys. Rev. Lett. Vol. 77, No. 13, 2774-2777 (1996). 154 Bibliography 130. Herranz, G. et al. "Enhanced electron-electron correlations in nanometric SrRuO3 epitaxial films". Phys. Rev. B Vol. 67, No. 17, 174423 (2003). 131. Herranz, G. et al. "Effect of disorder on the temperature dependence of the resistivity of SrRuO3". Phys. Rev. B Vol. 77, No. 165114 (2008). 132. Kumar, S. & Majumdar, P. "Singular effect of disorder on electronic transport in strongly coupled electron-phonon systems". Phys. Rev. Lett. Vol. 94, No. 13, 136601 (2005). 133. Millis, A. J., Hu, J. & Das Sarma, S. "Resistivity saturation revisited: results from a dynamical mean field theory". Phys. Rev. Lett. Vol. 82, No. 11, 2354-2357 (1999). 134. Iliev, M. N., Litvinchuk, A. P. et al. "Raman spectroscopy of SrRuO3 near the paramagnetic-to-ferromagnetic phase transition". Phys. Rev. B Vol. 59, No. 1, 364-368 (1999). 135. Yu, P. et al. "Interface ferromagnetism and orbital reconstruction in BiFeO3-La0.7Sr0.3MnO3 heterostructures". Phys. Rev. Lett. Vol. 105, No. 2, 027201 (2010). 136. Allen, P. B. et al. "Transport properties, thermodynamic properties, and electronic structure of SrRuO3". Phys. Rev. B Vol. 53, No. 8, 4393-4398 (1996). 137. Bushmeleva, S. N., Pomjakushin, V. Y., Pomjakushina, E. V., Sheptyakov, D. V. & Balagurov, A. M. "Evidence for the band ferromagnetism in SrRuO3 from neutron diffraction". J. Magn. Magn. Mater. Vol. 305, No. 2, 491-496 (2006). 138. Kumar, P. S. A., Joy, P. A. & Date, S. K. "On the irreversible magnetic behavior of the anisotropic ferromagnetic system SrRuO3". Physica B: Condensed Matter Vol. 269, No. 3–4, 356-361 (1999). 139. Mazin, I. & Singh, D. "Electronic structure and magnetism in Ru-based perovskites". Phys. Rev. B Vol. 56, No. 5, 2556-2571 (1997). 140. Yoo, Y. Z. et al. "Contribution of oxygen partial pressures investigated over a wide range to SrRuO3 thin-film properties in laser deposition processing". J. Appl. Phys. Vol. 97, No. 10, 103525 (2005). 155 Bibliography 141.Maria, J. P., Trolier-McKinstry, S., Schlom, D. G., Hawley, M. E. & Brown, G. W. "The influence of energetic bombardment on the structure and properties of epitaxial SrRuO3 thin films grown by pulsed laser deposition". J. Appl. Phys. Vol. 83, No. 8, 4373-4379 (1998). 142. Klenov, D. O., Donner, W., Foran, B. & Stemmer, S. "Impact of stress on oxygen vacancy ordering in epitaxial (La0.5Sr0.5)CoO3− δ thin films". Appl. Phys. Lett. Vol. 82, No. 20, 3427-3429 (2003). 143. Donner, W. et al. "Epitaxial Strain-Induced Chemical Ordering in La0.5Sr0.5CoO3−δ Films on SrTiO3". Chem. Mater. Vol. 23, No. 4, 984-988 (2011). 144. Gazquez, J. et al. "Lattice mismatch accommodation via oxygen vacancy ordering in epitaxial La0.5Sr0.5CoO3-δ thin films". APL Materials Vol. 1, No. 1, 012105 (2013). 145. Lu, W. et al. "The role of octahedral tilting in the structural phase transition and magnetic anisotropy in SrRuO3 thin film". J. Appl. Phys. Vol. 113, No. 6, 063901-063907 (2013). 146. Rondinelli, J. M. & Spaldin, N. A. "Substrate coherency driven octahedral rotations in perovskite oxide films". Phys. Rev. B Vol. 82, No. 11, 113402 (2010). 147. Boschker, H. et al. "Uniaxial contribution to the magnetic anisotropy of La0.67Sr0.33MnO3 thin films induced by orthorhombic crystal structure". J. Magn. Magn. Mater. Vol. 323, No. 21, 2632-2638 (2011). 148. Hatt, A. J. & Spaldin, N. A. "Structural phases of strained LaAlO3 driven by octahedral tilt instabilities". Phys. Rev. B Vol. 82, No. 19, 195402 (2010). 149. Rondinelli, J. M. & Coh, S. "Large isosymmetric reorientation of oxygen octahedra rotation axes in epitaxially strained perovskites". Phys. Rev. Lett. Vol. 106, No. 23, 235502 (2011). 150. Hong, J. & Vanderbilt, D. "Electrically driven octahedral rotations in SrTiO3 and PbTiO3". Phys. Rev. B Vol. 87, No. 6, 064104 (2013). 151. Mannhart, J. & Schlom, D. G. "Oxide interfaces - An opportunity for electronics". Science Vol. 327, No. 5973, 1607-1611 (2010). 156 Appendices APPENDICES List of Publications 1. Lu, W., Yang, P., Song, W. D., Chow, G. M. & Chen, J. S. Control of oxygen octahedral rotations and physical properties in SrRuO3 films. Phys. Rev. B 88, 214115 (2013) 2. Lu, W., Song, W. D., He, K., Chai, J., Sun, C. J., Chow, G. M. & Chen, J. S. The role of octahedral tilting in the structural phase transition and magnetic anisotropy in SrRuO3 thin film. J. Appl. Phys. 113, 063901 (2013). 3. Lu, W., He, K., Song, W. D., Sun, C. J., Chow, G. M. & Chen, J. S. Effect of oxygen vacancies on the electronic structure and transport properties of SrRuO3 thin films. J. Appl. Phys. 113, 17E125 (2013). 4. Lu, W., Song, W. D., Yang, P., Chow, G. M. & Chen, J. S. Strain engineering of octahedral rotations in SrRuO3 films. (to be submitted) 5. Zhang, B. M., Sun, C. J., Yang, P., Lu, W., Fisher, B. L., Venkatesan, T., Heald, S. M., Chen, J. S. & Chow, G. M. Strain modulated anisotropic electronic charge transfer in perovskite Pr0.67Sr0.33MnO3 thin films. (accepted in Physical Review B) 6. Liu, Z. Q., Lu, W., Zeng, S. W., Deng, J. W., Huang, Z., Li, C. J. et al. Bandgap controlling of oxygen-vancancy-induced two-dimensional electron gas in SrTiO3. (accepted in Advanced Materials Interfaces) 7. Si, H. Y., Lu, W., Chen, J. S., Chow, G. M., Sun, X. & Zhao J. Hydrothermal epitaxial multiferroic BiFeO3 thick film by addition to the PVA. J. Alloy. Compd. 577, 44 (2013). 8. Ke, Q. Q., Lu, W., Huang, X. L. & Wang, J. Highly (111)-oriented BiFeO3 thin film deposited on La0.67Sr0.33MnO3 buffered Pt/TiO2/SiO2/Si(100) substrate. J. Electrochem. Soc. 159, G11 (2012). 157 [...]... strain the tilting about film normal direction were enhanced and in- plane easy axis was preferred viii Summary Overall, this systematic study of octahedral rotation patterns in SrRuO3 films provides a comprehensive understanding of how the physical properties in SrRuO3 films are coupled to the octahedral rotations This coupling is promising for discovering and designing multifunctional phases in perovskite. .. oxides The successful manipulation of octahedral rotations in SrRuO3 films offers exciting opportunities to achieve desired properties and to generate new ground states in other perovskite films through adjusting the octahedral rotations Another contribution is the utilization of the half-integer reflections by synchrotron diffraction to gain insight into the octahedral rotation pattern in SrRuO3 films. .. rotations, leading to the suppression of the in- plane octahedral rotations in ultrathin films Thirdly, the effect of biaxial strain on the octahedral tilt of oxygen octahedra has been investigated The different levels of strain were introduced by using different single crystal substrates It was found that biaxial compressive strain favored octahedral rotations about the out -of- plane direction and out -of- plane... determination of octahedral rotations In addition, how the octahedral rotations are coupled to the physical properties of perovskite oxide thin films is still unknown In this study, three effective pathways have been developed to control the octahedral rotations in SrRuO3 (SRO) films The relationship between the octahedral rotations and the physical properties has also been investigated systematically... rotation of corner-sharing BO6 octahedra in perovskites modifies the B-O-B bond angles and critically affects the material properties. 14 However, rational control over octahedral rotations and physical properties experimentally has been rarely reported in spite of the recognized importance of octahedral rotations to properties partly due to the difficulties in carrying out a precise determination of octahedral. .. building block of the perovskite structure; (b) the high-temperature superconductor YBa2Cu3O7 with layered -perovskite structure.4 1.1.2 Physical Properties and Applications The physical properties of transition metal oxides of the ABO3 perovskite class vary enormously from one perovskite to another in spite of slight and obscure differences in crystal structure They cover a wide range of intriguing physical. .. brief introduction about the perovskite materials, octahedral rotation and its significant role in determining the physical properties The structural properties 1 Chapter 1 and physical properties of the SRO material investigated will also be briefly reviewed 1.1 Perovskite Materials Perovskite oxide materials are materials with the same type of crystal structure as calcium titanium oxide (CaTiO3) The interest... allows deep understanding into perovskite films, and helps elucidate the mechanisms of novel physical properties from the atomic level in perovskite films ix List of Tables LIST OF TABLES Table 1.1Tolerance factor ranges and the corresponding structure variants 5 Table 1.2 Complete list of possible simple tilt systems 13 Table 3.1 Summary of the structural parameters of SRO films deposited under... Effects of oxygen vacancies on octahedral tilts in the a) equatorial plane and b) apical plane in SRO films (a) Octahedral tilts about c axis are sustained while (b) the preference of oxygen vacancy (VO) in the SrO atomic plane results in a suppressed octahedral tilt about a and b axes (c), (d) Schematics of the interfacial couping of oxygen octahedra across an interface between two perovskite oxides... been investigated The aim of this research was to control the octahedral rotations and study how the rotations are coupled to the physical properties in perovskite films SrRuO3, a typical perovskite oxide whose octahedra rotate differently about each principle axis was chosen as a model material for this study All the SrRuO3 films were fabricated by pulsed laser deposition The crystal structure and . of Octahedral Rotations 13 1.2.3 Strain Engineering of Physical Properties 15 1.2.4 Determination of Octahedral Rotations 18 1.3 SrRuO 3 Thin Films 19 1.3.1 Structure of bulk SRO and thin. Identification of Octahedral Rotations 82 4.3.3 Control of Octahedral Rotations 87 4.3.4 Control of Physical Properties 93 4.4 Summary 101 CHAPTER 5 Control of Octahedral Rotations and Physical Properties. This coupling is promising for discovering and designing multifunctional phases in perovskite oxides. The successful manipulation of octahedral rotations in SrRuO 3 films offers exciting opportunities