Saengow Treetep, Silapunt Rardchawadee
Electronic and Telecommunication Engineering, King Mongkut's University of Technology Thonburi, 126 Prachauthit Rd., Thung Kru, Bangkok 10140, Thailand.
Micromachines (Basel). 2023 Jan 31;14(2):360. doi: 10.3390/mi14020360.
The geometry-dependent magnetoelectric (ME) and exchange bias (EB) effects of the nano ME sensor were investigated. The sensor consisted of the Longitudinal-Transverse (L-T) mode bi-layer bar structure comprising the ferromagnetic (FM) and ferroelectric (FE) materials and the anti-ferromagnetic (AFM) material. The bi-layer ME coefficient was derived from constitutive equations and Newton's second law. The trade-off between peak ME coefficient and optimal thickness ratio was realized. At the frequency × structure length = 0.1 and 1200, minimum and maximum peak ME coefficients of the Terfenol-D/PZT bi-layer were around 1756 and 5617 mV/Oe·cm, respectively, with 0.43 and 0.19 optimal thickness ratios, respectively. Unfortunately, the bi-layer could not distinguish the opposite magnetic field directions due to their similar output voltages. PtMn and CrO, the AFM, were introduced to produce the EB effect. The simulation results showed the exchange field starting at a minimum PtMn thickness of 6 nm. Nevertheless, CrO did not induce the exchange field due to its low anisotropy constant. The tri-layer ME sensor consisting of PZT (4.22 nm)/Terfenol-D (18 nm)/PtMn (6 nm) was demonstrated in sensing 2 Tbit/in magnetic bits. The average exchange field of 5100 Oe produced the output voltage difference of 12.96 mV, sufficient for most nanoscale magnetic sensing applications.
研究了纳米磁电（ME）传感器的几何相关磁电效应和交换偏置（EB）效应。该传感器由纵向 - 横向（L - T）模式双层棒结构组成，包括铁磁（FM）、铁电（FE）材料和反铁磁（AFM）材料。双层磁电系数由本构方程和牛顿第二定律推导得出。实现了峰值磁电系数与最佳厚度比之间的权衡。在频率×结构长度 = 0.1和1200时，Terfenol - D/PZT双层的最小和最大峰值磁电系数分别约为1756和5617 mV/Oe·cm，最佳厚度比分别为0.43和0.19。不幸的是，由于其输出电压相似，双层无法区分相反的磁场方向。引入反铁磁材料PtMn和CrO以产生交换偏置效应。模拟结果表明，交换场从最小PtMn厚度6 nm开始。然而，由于CrO的各向异性常数较低，它没有诱导出交换场。由PZT（4.22 nm）/Terfenol - D（18 nm）/PtMn（6 nm）组成的三层磁电传感器被证明可用于检测2 Tbit/in的磁比特。5100 Oe的平均交换场产生了12.96 mV的输出电压差，足以满足大多数纳米级磁传感应用。
