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arXiv · 2011.07508

Orbital gyrotropic magneto-electric effect and its strain engineering in monolayer Nb$X_2$

Sayantika Bhowal·S. Satpathy
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Abstract

Electrical control of the orbital degrees of freedom is an important area of research in the emerging field of "orbitronics." Orbital {\it gyrotropic} magneto-electric effect (OGME) is the generation of an orbital magnetization in a nonmagnetic metal by an applied electric field. Here, we show that strain induces a large GME in the monolayer Nb$X_2$ ($X =$ S, Se) normal to the plane, primarily driven by the orbital moments of the Bloch bands as opposed to the conventional spin magnetization, without any need for spin-orbit coupling. The key physics is captured within an effective two-band valley-orbital model and it is shown to be driven by three key ingredients: the intrinsic valley orbital moment, broken $C_{3z}$ symmetry, and strain-induced Fermi surface changes. The effect can be furthermore switched by changing the strain condition, with potential for future device applications.

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Sayantika Bhowal, S. Satpathy. 2020-11-15. Orbital gyrotropic magneto-electric effect and its strain engineering in monolayer Nb$X_2$. https://doi.org/10.1103/physrevb.102.201403

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