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arXiv 2201.05807cond-mat.mes-hall
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晶体中的轨道霍尔效应:原子间和原子内贡献

Orbital Hall effect in crystals: inter-atomic versus intra-atomic contributions

Armando Pezo, Diego Garcia Ovalle, Aurelien Manchon

摘要:

轨道霍尔效应(OHE)表示横向于初始电荷电流的轨道角动量的电荷中性流的产生。最近的理论研究表明,过渡金属显示出相当大的OHE,鼓励沿着这个方向进行实验研究。尽管如此,这些理论中的大多数都假定轨道矩来自原子核周围的区域,采用所谓的{ \it原子中心近似}。然而,在周期性晶体中,间隙区域的贡献是至关重要的,并且可能导致对OHE的严重错误估计。通过应用“现代理论”的轨道磁化的OHE,我们评估原子内和原子间的贡献,在选定的材料从第一原理的相对重要性。我们发现,虽然OHE主要是宽带隙半导体的原子内起源(例如,MoS $_2$),原子间贡献在窄带隙半导体(SnTe、PbTe)和过渡金属(Pt、V等)中变得至关重要。这些预测使以前的一些工作中采用的原子中心近似失效,并为实现有效的轨道电流源开辟了前景。

英文摘要:

The orbital Hall effect (OHE) designates the generation of a charge-neutral flow of orbital angular momentum transverse to an initial charge current. Recent theoretical investigations suggest that transition metals display sizable OHE, encouraging experimental search along this direction. Nonetheless, most of these theories assume that the orbital moment originates from the region immediately surrounding the atom core, adopting the so-called {\it atomic center approximation}. In periodic crystals though, the contribution of the interstitial regions is crucial and can lead to a severe misestimation of the OHE. By applying the "modern theory" of orbital magnetization to the OHE, we assess the relative importance of intra-atomic and inter-atomic contributions in selected materials from first principles. We find that whereas the OHE is mostly of intra-atomic origin for wide band-gap semiconductors (e.g., MoS$_2$), the inter-atomic contribution becomes crucial in narrow band-gap semiconductors (SnTe, PbTe) and transition metals (Pt, V etc.). These predictions invalidate the atomic center approximation adopted in some of the previous works and open perspectives for the realization of efficient sources of orbital currents.

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