Tirion Sytze H, van Wees Bart J
Zernike Institute for Advanced Materials, University of Groningen, NL-9747AG Groningen, The Netherlands.
ACS Nano. 2024 Feb 27;18(8):6028-6037. doi: 10.1021/acsnano.3c12925. Epub 2024 Feb 14.
Significant attention has been drawn to electronic transport in chiral materials coupled to ferromagnets in the chirality-induced spin selectivity (CISS) effect. A large magnetoresistance (MR) is usually observed, which is widely interpreted to originate from spin (dependent) transport. However, there are severe discrepancies between the experimental results and the theoretical interpretations, most notably the apparent failure of the Onsager reciprocity relations in the linear response regime. We provide an alternative mechanism for the two terminal MR in chiral systems coupled to a ferromagnet. For this, we point out that it was observed experimentally that the electrostatic contact potential of chiral materials on a ferromagnet depends on the magnetization direction and chirality. The mechanism that we provide causes the transport barrier to be modified by the magnetization direction, already in equilibrium, in the absence of a bias current. This strongly alters the charge transport through and over the barrier, not requiring spin transport. This provides a mechanism that allows the linear response resistance to be sensitive to the magnetization direction and also explains the failure of the Onsager reciprocity relations. We propose experimental configurations to confirm our alternative mechanism for MR.
在手性诱导自旋选择性（CISS）效应中，与铁磁体耦合的手性材料中的电子输运已引起了广泛关注。通常会观察到很大的磁电阻（MR），人们普遍认为这源于自旋（相关）输运。然而，实验结果与理论解释之间存在严重差异，最明显的是在线性响应区域中昂萨格互易关系明显失效。我们为与铁磁体耦合的手性系统中的两终端磁电阻提供了一种替代机制。为此，我们指出实验观察到铁磁体上手性材料的静电接触电势取决于磁化方向和手性。我们提供的机制会使输运势垒在平衡状态下、在没有偏置电流的情况下就被磁化方向改变。这极大地改变了通过势垒及越过势垒的电荷输运，而不需要自旋输运。这提供了一种机制，使得线性响应电阻对磁化方向敏感，也解释了昂萨格互易关系的失效。我们提出了实验配置来证实我们关于磁电阻的替代机制。
