直播预告 | 哈工大陈晓彬教授：基于自旋-谷失配材料的巨隧穿磁电阻效应

本次分享将解读发表于顶刊Physical Review Letters 与npj Computational Materials 的最新成果：

半金属可实现完美的自旋过滤效应，因此被广泛应用于高磁阻器件的研发。然而，目前可用的半金属材料种类极为有限。本研究证明，具有本征自旋 - 谷失配（SVM）态的材料能够阻断电荷输运，其行为与半金属相似，进而可产生巨隧穿磁电阻效应。

作为例证，通过第一性原理输运计算我们发现：铁磁性的 1T-VSe₂、1T-VS₂和 2H-VS₂均属于此类自旋 - 谷失配金属；以这些金属作为电极构建的自旋阀范德华（vdW）结，可实现超过 99% 的巨大磁阻（悲观定义）。另一个典型例子是交替磁体 KV₂Se₂O：以金属性 KV₂Se₂O 为电极、少层 MgO 为势垒层的磁性隧道结，其零偏压磁电阻同样大于 99%，且该性能对偏置电压和势垒层厚度具有良好的鲁棒性。

得益于自旋态的本征失配特性，范德华结的中心层材料原则上可以是任意非磁性材料。本研究为高磁阻效应的物理机制提供了清晰的阐释，同时为高磁阻器件的材料筛选与设计开辟了全新方向。

Half metals, which are amenable to perfect spin filtering, can be utilized for high-magnetoresistive devices. However, available half metals are very limited. Here, we demonstrate that materials with intrinsic spin-valley-mismatched (SVM) states can be used to block charge transport, resembling half metals and leading to giant tunneling magnetoresistance. As an example, by using first-principles transport calculations, we show that ferromagnetic 1T-VSe2, 1T-VS2, and 2H-VS2 are such spin-valley-mismatched metals, and giant pessimistic magnetoresistance of more than 99% can be realized in spin-valve van der Waals (vdW) junctions using these metals as electrodes. Another example is the altermagnet KV2Se2O. We show that magnetic tunnel junctions using the metallic KV2Se2O as the electrodes and few-layer MgO as the spacer exhibit zero-bias magnetoresistance larger than 99%, which is robust against the bias and thickness of the spacer. Owing to the intrinsic mismatch of spin states, the central-layer materials for the vdW junctions can be arbitrary nonmagnetic materials, in principle. Our research provides clear physical insights into the mechanism for high magnetoresistance and opens new avenues for the search and design of high-magnetoresistance devices.

欢迎从事凝聚态物理、自旋电子学、材料科学等领域的师生、科研工作者及产业界同仁参会交流，也欢迎转发给身边感兴趣的同行！

活动发起人：Somananda Sanyal、Jayita Patwari、Stefan Hildebrandt、李佳琪、 王欢