La-Ba-Mn-O陶瓷材料的阻抗与巨磁阻抗研究

Investigation of Impedance and Giant Magnetoimpedance for La-Ba-Mn-O Ceramic Oxide

摘要: 本文研究了1200℃退火10小时后得到的La0.65Ba0.35MnO3块状陶瓷材料在室温下的交流阻抗以及巨磁阻抗(GMI)效应。巨磁阻抗效应显示出了强烈的频率依赖关系。在室温下及H = 500 Oe的外加磁场下，样品可显示出很强的交流巨磁电阻、巨磁电抗、巨磁阻抗效应：DR/R0 = −25.1% (f = 20 MHz)，DX/X0 = −22% (f = 100 kHz)以及DZ/Z0 = −17.4% (f = 9 MHz)。利用电磁理论结合铁磁学原理, 可对锰氧化物陶瓷材料阻抗与磁阻抗现象给出很好的物理理解。我们同时发现1200℃退火10小时后得到的La0.65Ba0.35MnO3块状陶瓷材料在f £ 20 MHz时，DZ/Z0随磁场单调下降，这说明该材料磁横向各向异性很小可忽略。DZ/Z0随磁场单调变化的特点有利于磁传感器的器件设计。

Abstract: In this paper, the impedance and magnetoimpedance for La0.65Ba0.35MnO3 sol-gel material annealed at 1200˚C for 10 h have been investigated at room temperature. This material shows the large giant magnetoimpedance (GMI) effect with strong fervency dependence. The material exhibits the ac magnetoresistance DR/R0 = −25.1% at f = 20 MHz, ac magnetoreactance DX/X0 = −22% at f = 100 kHz, and magnetoimpedance DZ/Z0 = −17.4% at f = 9 MHz under a weak magnetic field H = 500 Oe at room temperature. The impedance and magnetoimpedance effect can be well described with electrodynamics and ferromagnetism principle. We also find that La0.65Ba0.35MnO3 sol-gel material annealed at 1200˚C for 10 h shows a monotonic magnetoimpedance in the frequency range f £ 30 MHz, showing a weak and negligible transverse magneto-anisotropy field in the sample. Such monotonic GMI behavior is beneficial to the design of GMI magnetic sensor.