DSpace at VNU: Magnetoelectric sensor for microtesla magnetic-fields based on (Fe80Co20)(78)Si12B10 PZT laminates

Sensors and Actuators A 149 (2009) 229–232 Contents lists available at ScienceDirect Sensors and Actuators A: Physical journal homepage: www.elsevier.com/locate/sna Magnetoelectric sensor for microtesla magnetic-fields based on (Fe80 Co20 )78 Si12 B10 /PZT laminates D.T Huong Giang ∗ , N.H Duc Laboratory for Nano Magnetic Materials and Devices, Faculty of Engineering Physics and Nanotechnology, College of Technology, Vietnam National University, Hanoi, E3 Building, 144 Xuan Thuy Road, Cau Giay, Hanoi, Vietnam a r t i c l e i n f o Article history: Received 23 May 2008 Received in revised form December 2008 Accepted December 2008 Available online 11 December 2008 Keywords: Magnetic sensor Magnetoelectric Magnetostrictive Piezoelectric Multiferroics a b s t r a c t The magnetoelectric sensor based on (Fe80 Co20 )78 Si12 B10 /PZT laminates is designed, fabricated and characterized for determining dc and ac magnetic-field strengths as well as field orientations At low dc magnetic-fields, a ME-voltage response (dVME /dH) as high as mV/Oe is achieved The linear relation VME (hac ) with a slope of dVME /dhac of 17 mV/Oe shows a great ability to self-powered detecting low ac magnetic-fields The field orientation can be detected by using the sinusoidal dependence of the magnetoelectric voltage The sensor is promising not only for microtesla magnetic-field sensing but also for magnetic biosensor applications © 2008 Elsevier B.V All rights reserved Introduction Traditional Hall and magnetoresistive effect based magneticfield sensors always need to provide for the power supply, which raises some deficiencies In this context, self-powered magneticfield sensors transferring directly magnetic energy into electrical signal are of great interest Such sensors can be realized thanks to the magnetoelectric (ME) effect, which is observed in multiferroics and/or ferromagnetic-ferroelectric composites (hereafter denoted as ME materials) In these materials, an electric polarization P can respond to an applied magnetic-field H, or conversely a magnetization M can respond to an applied electric field E In applied dc magnetic-fields, a ME sample undergoes poling that creates an electric field E = ˛E H, where ˛E denotes the magnetoelectric voltage coefficient As a results, a ME-voltage VME = tE (= ˛E tH) appears between the surface of the sample with thickness t Large magnetoelectric voltage coefficients ˛E (=dE/dH = VME /hac t) offer potential device applications as highly sensitive magnetic-field sensors, microwave filters, transformers, gyrators, etc [1] As regards the high magnetoelectric voltage coefficients, multiferroic composites using magnetostrictive ferrites and rare earth – transition intermetallic compounds have been studied intensively ∗ Corresponding author Tel.: +84 754 9332; fax: +84 754 7460 E-mail address: giangdth@vnu.edu.vn (D.T.H Giang) 0924-4247/$ – see front matter © 2008 Elsevier B.V All rights reserved doi:10.1016/j.sna.2008.12.003 from the beginning of this century [2–8] In particular, the design, operation principles and characteristics of this new ME sensor were also reported The value of magnetic-field responsibility dVME /dH as high as 0.06 mV/Oe, 56 mV/Oe and 13 mV/Oe were achieved for MEcomposite based magnetic-field sensors using the magnetostrictive Ni0.5 Zn0.5 Fe2 O4 ferrite [2], Terfenol-D laminate [6] and Terfecohan thin film [7], respectively In addition, the ME-sensors can apply to determine the strength of ac magnetic-field In this case, Dong et al [8] have developed a promising generation of extremely low frequency magnetic-field sensors to achieve sensitivities of 10−7 T and below in the mHz frequency range This paper presents our design, working modes and induced ME voltage behavior of a self-powered magnetoelectric sensor for micro-Tesla magnetic-fields based on (Fe80 Co20 )78 Si12 B10 /PZT laminates We will show that our sensor can be applied to measure the strength of both dc and ac magnetic-fields as well as magnetic-field orientation Sensor construction The ME composite under investigation is formed by using self-fabricated melt spinning mm-wide and 30 ␮m-thick magnetostrictive (Fe80 Co20 )78 Si12 B10 ribbon sheets magnetized along the longitudinal (or length) direction and an out-of-plane poled piezoelectric PZT plate (APCC-855) with thickness tPZT = 200 ␮m supplied by the American Piezoceramics Inc The optimum design for the ME composite based magnetic-field sensor is realized with the configuration using two magnetostrictive 450 ◦ C-annealed FeCoBSi ribbon 230 D.T.H Giang, N.H Duc / Sensors and Actuators A 149 (2009) 229–232 Fig Schematic illustrations of a ME sensor prototype based on the magnetostrictive/piezoelectric composite operating in the longitudinal–transversal (L–T) mode (left) and the definition for the angle ϕ between the (longitudinal) applied magnetic-fields and (transverse) poled electrical polarization direction of the multiferroic FeCoBSi/PZT composite used in present sensor design (with double ribbon sheets on each outer side) (right) sheets bonded on both two sides of PZT plate (Fig 1, left) Presently, the FeCoBSi ribbon is known as a soft magnetostrictive material with the (saturation) magnetostriction s ∼ 70 × 10−6 and (par= d /dH ∼ 1.5 × 10−6 Oe−1 allel) magnetostrictive susceptibility Thanks to mechanically coupling between these components, when the magnetostrictive layers are strained under applied in-plane (and/or out-of-plane) magnetic-fields, the PZT plate will undergo a forced strain In this case, the ME-voltage VME is induced across the thickness of the piezoelectric plate Practically, the VME is measured directly as a response of the ME composite to an ac magnetic-field hac (=h0 sin(2 f0 t)) in a dc bias field H (see also Fig 1, right) Shown in Fig are photographs of the ME based sensor prototype Here, the coil generating the alternating field hac (called as ac field coil) is directly wrapped around the ME composite with dimension of × mm (Fig 2a) For this construction, the ac magnetic-field is always aligned in the PZT plane, i.e always perpendicular to the (poled) electrical polarization In this experimental setup, an electrical polarization is induced by a weak ac magnetic-field hac oscillating at resonant frequency of kHz in the presence of a dc bias field H provided by an electromagnet A lock-in amplifier (7265 DSP) is used to generate a controllable input current to the ac field coil and to measure the output voltage (VME ) induced across the PZT layer Fig Sensor response as a function of bias magnetic-fields Sensor operations The fabricated sensor can operate in a (dc and ac) magneticfield strength sensing mode as well as magnetic-field orientation sensing one To determine the strength of the dc magnetic-field, the sensor is simply used in the configuration of the dc magnetic- Fig Sensor construction: FeCoBSi/PZT laminate (a), internal structure of magnetic sensor where the coil generating an ac field directly wrapps around the ME laminates (b) and the sensor prototype (c) D.T.H Giang, N.H Duc / Sensors and Actuators A 149 (2009) 229–232 fields aligned parallel to the ac magnetic-field (i.e for ϕ = 90◦ ) In this case, the dc magnetic-field strength dependence of the MEvoltage of the sensor measured in hac = Oe is presented in Fig It can be seen from this figure that the signal increases in a near linear manner with increasing H over the range < H < 100 Oe and gradually approaches to the maximum value of about 220 mV, corresponding to a value of the magnetoelectric voltage coefficient ˛E = 2050 mV/cm Oe With further increase of the field, the VME decreases gradually and falls to zero when the field increases up to 350 mT This observation can be understood in term of the strong relation between ME voltage and the magnetostrictive susceptibility (d /dH) of the magnetic ribbon, VME ∼ d /dH [5] The vanishing of VME can be attributed to the magnetostriction saturation tendency at high field (d /dH = 0) [7] For low magnetic-field sensing applications, it is worth noting that the sensor exhibits an extremely high voltage response (dVME /dH) of about mV/Oe This result is rather promising for micro-Tesla magnetic-field sensors, in particular, for magnetic biosensors, where only a sensitivity of about ␮V/Oe is achieved by using traditional Hall and magnetoresistive effects [9,10] 231 Fig Demonstration of ability of the ME sensor to detect low ac magnetic-fields in the bias magnetic-field of 65 Oe measured in the case of ϕ = 90◦ Fig The V(ϕ) dependence of the sensors measured in different magnetic-field values (left) and the data plotted as a function of effective in-plane magnetic-field component Heff = Hsinϕ and compared to the those (straight line) measured for ϕ = 90◦ as given in Fig 232 D.T.H Giang, N.H Duc / Sensors and Actuators A 149 (2009) 229–232 Fig illustrates the induced ME-voltage as a function of hac in the bias field H = 65 Oe measured in the configuration of ϕ = 90◦ Clearly, the VME is linearly proportional to hac and exhibits the value of dVME /dhac = 17 mV/Oe The value of the ME voltage varies depending on the magnetic biases and frequencies The inspection of this result, however, reveals an ability to detect low ac magneticfield strength In this case, the sensor is actually self-powered, and provides direct conversion of ac magnetic-field into an electrical signal The sensor response is sensitive not only to the strength of magnetic-fields but also to their orientation Shown in Fig (left) are plots of the ME voltage as a function of angle ϕ between external dc magnetic-field and thickness direction (see Fig 1, right) measured at several bias magnetic-fields of H = 80, 140, 200 and 500 Oe It is seen from this figure that although the VME (ϕ) exhibits different variation tendencies, but for all cases the ME signal varies periodically with ϕ The VME (ϕ) is perfectly characterized by a sinus behavior for H = 80 Oe (and/or magnetic-field strengths below maximum appeared in Fig 3) It changes to a trapezoid-, M- and well-sharp in H = 150, 200 and 500 Oe, respectively These complex VME (ϕ) peak inflection, however, can be described well in terms of the effective in-plane magnetic-field component Heff = Hsinϕ Indeed, the obtained VME (ϕ) data can be transferred into the plot of VME (Hsinϕ) and presented in Fig (right) Clearly, it reproduces well the experimental data (solid line), which already reported in Fig for magnetic-fields aligned in plane of the ribbon (i.e for ϕ = 90◦ ) The periodical variation of the output signal with respect to ϕ opens the ability to use this sensor for detecting the orientation of the external magnetic-field For this purpose, we prefer to apply the results obtained in bias magnetic-fields less than 80 Oe, where the sinus behavior was found only for microtesla magnetic-field sensing but also for magnetic biosensor applications For a real biosensor application to detect magnetic labels, this sensor is required to diminish in micrometersize However, the project is still in progress Acknowledgements This work was supported by the Fundamental Research Program of Vietnam under the Project 410.406 and the Vietnam National University, Hanoi under the project QC 07.07 References [1] T.H O’Dell, Magnetoelectrics-a new class of materials, Electron Power 11 (1965) 266–267 [2] L.P.M Bracke, R.G van Vliet, A broadband magneto-electric transducer using a composite material, Int J Electron 51 (1981) 255–262 [3] B.J Linch, H.R Gallantree, A new magnetic sensor technology, GEC J Res (1990) 13–20 [4] M.I Bichurin, V.M Petrov, R.V Petrov, Y.U.V Kiliba, F.I Bukashev, A.Y.U Smirnov, D.N Eliseev, Magnetoelectric sensor of magnetic field, Ferroelectric 280 (2002) 199–202 [5] Y Fetisov, A Bush, K Kamentsev, A Ostashchenko, G Srinivasan, Magnetic field sensors using magnetoelectric effects in ferrite piezoelectric multilayers, Proceedings of IEEE Sensors (2004) 1106–1108 [6] D Shuxiang, Li Jie-Fang, D Viehland, Characterization of magnetoelectric laminate composites operated in longitudinal-transverse and transverse–transverse modes, J Appl Phys 95 (2004) 2625–2630 [7] N.H Duc, D.T Huong Giang, Magnetic sensors based on piezoelectric– magnetostrictive composites, J Alloys Compd 449 (2008) 214–218 [8] D Shuxiang, Z Junyi, Zhengping, Li Jie-Fang, D Viehland, Extremely low frequency response of magnetoelectric multilayer composites, Appl Phys Lett 86 (2005) 102901 [9] L Ejsing, M.F Hansen, A.K Menon, H.A Ferreira, D.L Graham, P.P Freitas, Magnetic micro-beadedetection using the planar Hall effect, J Magn Magn Mater 293 (2005) 677–684 [10] N.T Thanh, B Parvatheeswara Rao, N.H Duc, C.G Kim, Planar Hall resistance sensor for biochip application, Physica Status Solidi (a) 204 (2007) 4053–4057 Conclusions Biographies In summary, a magnetoelectric sensor based on (Fe80 Co20 )78 Si12 B10 /PZT laminates has been designed, fabricated and characterized The sensor can operate to determine the dc and ac magnetic-field strength as well as to sense the field orientation The results have shown that at low dc fields, a ME-voltage response (dVME /dH) as high as mV/Oe is achieved Besides, a linear relation between the induced ME-voltage and ac magnetic-fields is observed It reveals the ability of the sensor for self-powered detecting low ac magnetic-fields In addition, by using a charge amplifier, this magnetoelectric sensor can also be fully self-powered for dc magnetic-field detection, i.e without any requirements of ac magnetic-fields to modulating the signals Finally, the sensor response is sensitive not only to the field strength but also to the field orientation In this case the field orientation can be detected by using the sinus behavior of the VME (ϕ) This sensor is promising not D.T Huong Giang received her BSc degree in Materials Science from College of Science, Vietnam National University Hanoi in 2001 and PhD degree in Physics from the Rouen University, France in 2005 Her research interests include magnetostrictive, magnetoresistance and magnetoelectric materials, multiferroics, sensors and devices In 2006, she joined the Faculty of Engineering Physics and Nanotechnology at the College of Technology, Vietnam National University Hanoi, where she is currently an assistant professor N.H Duc joined the Cryogenic Laboratory, University of Hanoi as researcher after his graduation from the group in 1980 He obtained his doctor degree in the same group in 1988 He has received the French Habilitation in Physics at the Joseph Fourier University of Grenoble in 1997 and became a full professor of the College of Technology, Vietnam National University, Hanoi in 2004 In the period passed he extended his research on various aspects of magnetism, such as: 4f–3d exchange interactions; giant magnetovolume, magnetostrictive, magnetoresistive and magnetocaloric effects; magnetic phase transition; magnetic nanostructures; multiferroics; MERAM and biochips  ... magnetic-field orientation sensing one To determine the strength of the dc magnetic-field, the sensor is simply used in the configuration of the dc magnetic- Fig Sensor construction: FeCoBSi /PZT laminate (a),... behavior was found only for microtesla magnetic-field sensing but also for magnetic biosensor applications For a real biosensor application to detect magnetic labels, this sensor is required to... magnetostriction saturation tendency at high field (d /dH = 0) [7] For low magnetic-field sensing applications, it is worth noting that the sensor exhibits an extremely high voltage response (dVME