论文标题
一个电子计数规则，用于确定范德华材料的层间磁耦合
An electron-counting rule to determine the interlayer magnetic coupling of the van der Waals materials
论文作者
论文摘要
在分层的磁性材料中，相邻的范德华层之间的磁耦合要具有挑战性地理解和预期，尽管层内的交换相互作用可以很好地理解合理化，例如通过superexchange机制。在这项工作中，我们阐明了层间交换机制，并提出了一项电子计数规则，以确定范德华层之间的层间磁序，以计算$ d $ - 轨道职业（$ d^n $，其中$ n $是磁心上的$ d $ -Electrons的数量）。使用此规则，我们将磁性单层分为两组，即I型（$ n <5 $）和II型（$ n \ geq5 $），并为绝缘子和金属提供了三种类型的层间磁耦合。两个类型II层之间的耦合更喜欢抗铁磁（AFM）阶，而I型和II型接口则有利于铁电磁（FM）方式。但是，对于两种I层，它们显示了FM和AFM订单之间的竞争，甚至导致堆叠依赖性磁性。此外，通过自由载体跳跃的较小校正，也可以将金属层纳入该规则中。因此，该规则提供了简单的指导，以了解带有所需磁性秩的层间交换和进一步的设计范德华连接。
In layered magnetic materials, the magnetic coupling between neighboring van der Waals layers is challenging to understand and anticipate, although the exchange interaction inside a layer can be well rationalized for example by the superexchange mechanism. In this work, we elucidate the interlayer exchange mechanism and propose an electron-counting rule to determine the interlayer magnetic order between van der Waals layers, based on counting the $d$-orbital occupation ($d^n$, where $n$ is the number of $d$-electrons at the magnetic cation). With this rule, we classify magnetic monolayers into two groups, type-I ($n<5$) and type-II ($n\geq5$), and derive three types of interlayer magnetic coupling for both insulators and metals. The coupling between two type-II layers prefers the antiferromagnetic (AFM) order, while type-I and type-II interfaces favor the ferromagnetic (FM) way. However, for two type-I layers, they display competition between FM and AFM orders and even lead to the stacking dependent magnetism. Additionally, metallic layers can also be incorporated into this rule with a minor correction from the free carrier hopping. Therefore, this rule provides simple guidance to understand the interlayer exchange and further design van der Waals junctions with desired magnetic orders.
