Mathematical modeling of the magnetoelectric effect of the nano bi-layer L-T mode bar structure in high frequency regime

Treetep Saengow,Rardchawadee Silapunt,Salinee Choowitsakunlert

doi:10.1007/s00542-020-05150-8

Treetep Saengow, Rardchawadee Silapunt + Show 1 more

Open Access

https://doi.org/10.1007/s00542-020-05150-8

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Abstract

This paper describes the magnetoelectric (ME) coupling behavior of the nano bi-layer L-T (longitudinal-transverse) mode bar structure through the ME coefficient mathematical model that is developed in high frequency regime. Terfenol-D and Lead Zirconate Titanate (PZT) are used as ferromagnetic (FM) and ferroelectric (FE) layers, respectively. The ME coefficients are determined at different layer thickness ratios and products of the operating frequency (f) and structure length (l). It is found that the ME coefficient and optimal thickness ratio increases and decreases exponentially respectively, with fl. The minimum and maximum peak ME coefficients at fl values of 0.1 and 1,200 respectively, are around 1,756 and 5,617 mV/Oecdot cm with the optimal thickness ratio of 0.43 and 0.19, respectively. The ME coupling behavior depends largely on the magnetostrictive effect in the FM layer that is altered by the applied magnetic field and fl. The demonstration as the read sensor for the hard disk drive (HDD) with 2 Tbit/in2 areal density and 190 Oe/bit applied magnetic field shows the output voltage across the FE layer of around 0.43 mV, which is more than sufficient for the raw signal readback.

Highlights

Research on magnetoelectric (ME) materials has been growing dramatically owing to the material’s potential for high frequency applications such as magnetic sensing in memory or storage devices and current-to-voltage conversion Vopsaroiu et al (2007); Palneedi et al (2006); Choowitsakunlert et al (2014); Nan et al (2008)
This paper describes the magnetoelectric (ME) coupling behavior of the nano bi-layer L-T mode bar structure through the ME coefficient mathematical model that is developed in high frequency regime
The ME material is made of multiferroic composites that possess direct and converse ME coupling effects, which are the induction of electric polarization by the magnetic field and the induction of magnetization by the electric field, respectively Palneedi et al (2006); Saengow et al (2018); Wang et al (2010)

Summary

Introduction

Research on magnetoelectric (ME) materials has been growing dramatically owing to the material’s potential for high frequency applications such as magnetic sensing in memory or storage devices and current-to-voltage conversion Vopsaroiu et al (2007); Palneedi et al (2006); Choowitsakunlert et al (2014); Nan et al (2008). There were several studies on developing mathematical models of the ME coefficient of the nano heterostructures with different input-output field orientations and operating modes such as L-T (longitudinal-transverse) and T-T (transverse-transverse) modes with bar and plate structures, respectively Vopsaroiu et al (2007); Saengow et al (2018); Wang et al (2010); Saengow and Silapunt (2020). For the L-T mode, the external magnetic field is applied to the FM layer in a longitudinal direction in order to induce the mechanical strain in the same direction. For the proposed nano bi-layer structure, perfect physical bonding between the FM layer and the FE layer and uniformly applied magnetic field are assumed This external magnetic field induces the mechanical strain in the longitudinal direction that results in equal elastic displacements (n) in both layers. By rearranging Eq (22), the ME coefficient, which is the ratio between the induced electric field and the applied magnetic field, can be found as shown in Eq (23)

ME coupling behavior of Terfenol-D and PZT bi-layer bar structure

Demotration of the nano bi-layer structure as a magnetic read head for HDD

Conclusions