GdSi单晶中可能的磁极化子开关正、负磁电阻效应
Possible magnetic-polaron-switched positive and negative magnetoresistance in the GdSi single crystal
摘要：
磁电阻（MR）的可能的技术应用引起了极大的关注。理解磁在操纵MR中的作用，反过来可以引导寻找新的适用MR材料。在这里，我们表明，反铁磁（AFM）GdSi金属显示各向异性的正MR值（PMRV），高达$\sim$ 415%，伴随着一个大的负热体积膨胀（NTVE）。在$T_\text{N}$附近，PMRV转换为负值，降至$\sim$-10.5%。他们打破理论的磁场依赖性[PMRV：主要是线性的;负MR值（NMRV）：二次的]和不寻常的NTVE表明，PMRV是由5个$d$带中磁极化子的形成引起的，而NMRV可能是由于磁场对准的局部4个$f$自旋导致的电子自旋散射减弱。我们的研究结果可能开辟了一条新的途径，寻找巨大的MR材料，通过抑制AFM转变温度，相反的情况下，在锰氧化物，并提供了一个有前途的方法，以新颖的磁性和电气设备。
英文摘要：
Magnetoresistance (MR) has attracted tremendous attention for possible technological applications. Understanding the role of magnetism in manipulating MR may in turn steer the searching for new applicable MR materials. Here we show that antiferromagnetic (AFM) GdSi metal displays an anisotropic positive MR value (PMRV), up to $\sim$ 415%, accompanied by a large negative thermal volume expansion (NTVE). Around $T_\text{N}$ the PMRV translates to negative, down to $\sim$ -10.5%. Their theory-breaking magnetic-field dependencies [PMRV: dominantly linear; negative MR value (NMRV): quadratic] and the unusual NTVE indicate that PMRV is induced by the formation of magnetic polarons in 5$d$ bands, whereas NMRV is possibly due to abated electron-spin scattering resulting from magnetic-field-aligned local 4$f$ spins. Our results may open up a new avenue of searching for giant MR materials by suppressing the AFM transition temperature, opposite the case in manganites, and provide a promising approach to novel magnetic and electric devices.
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