Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA.
Oak Ridge National Laboratory, Center for Nanophase Materials Sciences, Oak Ridge, Tennessee 37831, USA.
Nat Commun. 2015 Jan 7;6:5959. doi: 10.1038/ncomms6959.
In numerous systems, giant physical responses have been discovered when two phases coexist; for example, near a phase transition. An intermetallic FeRh system undergoes a first-order antiferromagnetic to ferromagnetic transition above room temperature and shows two-phase coexistence near the transition. Here we have investigated the effect of an electric field to FeRh/PMN-PT heterostructures and report 8% change in the electrical resistivity of FeRh films. Such a 'giant' electroresistance (GER) response is striking in metallic systems, in which external electric fields are screened, and thus only weakly influence the carrier concentrations and mobilities. We show that our FeRh films comprise coexisting ferromagnetic and antiferromagnetic phases with different resistivities and the origin of the GER effect is the strain-mediated change in their relative proportions. The observed behaviour is reminiscent of colossal magnetoresistance in perovskite manganites and illustrates the role of mixed-phase coexistence in achieving large changes in physical properties with low-energy external perturbation.
在许多系统中，当两种相共存时，会发现巨大的物理响应；例如，在相变附近。一种金属间 FeRh 系统在室温以上经历一级反铁磁到铁磁转变，并在相变附近表现出两相共存。在这里，我们研究了电场对 FeRh/PMN-PT 异质结构的影响，并报告了 FeRh 薄膜电阻率变化 8%。在金属系统中，这种“巨大”的电阻变化（GER）响应引人注目，因为外部电场被屏蔽，因此对载流子浓度和迁移率的影响较弱。我们表明，我们的 FeRh 薄膜由具有不同电阻率的共存铁磁和反铁磁相组成，GER 效应的起源是它们相对比例的应变介导变化。观察到的行为让人联想到钙钛矿锰氧化物中的庞磁电阻，并说明了混合相共存在实现低能量外部扰动下物理性质的大幅变化中的作用。
