Pristine materials seldom appear as we want them. Instead, their appeal typically comes from suitable modifications. Proximity effects are a versatile method to transform a given material by acquiring the properties of its neighbors and becoming, superconducting, magnetic, valley-polarized, or topologically nontrivial [1-3]. This approach is particularly suitable for 2D materials in which the length of the proximity effects exceeds their thickness [1,2]. Advances in (quantum) spin and anomalous Hall effect, as well as (anomalous) valley Hall effect suggest the electronic degrees of freedom (spin, charge and valley) can be used as different information carriers . The realization of multiple Hall effects in a single material provides a fascinating opportunity to manipulate the implementation of such information. Here we predict the realization and manipulation of multiple Hall effects in the proximitized 2D materials based on first-principles calculations and tight binding models. Harnessing such Hall effects associated with multiple degrees of freedom of electrons could enable novel applications in electronics, spintronics, and valleytronics.
. P. Lazić, K. D. Belashchenko, I. Žutić, Phys. Rev. B 2016, 93, 241401.
. B. Scharf, A. Matos-Abiague, J. E. Han, E. M. Hankiewicz, I. Žutić, Phys. Rev. Lett. 2016, 117, 166806.
. T. Zhou, J. Zhang, Y. Xue, B. Zhao, H. Zhang, H. Jiang, Z. Yang, Phys. Rev. B 2016, 94, 235449.
The injection of spin polarized carriers in semiconductor lasers greatly modifies the device operation. Although the vast majority of spin lasers are based on semiconductors with zinc-blende structure, there is a recent exception using nitride-based compounds with wurtzite structure, which still lacks a reliable theoretical description. In order to address such deficiency, we investigated (In,Ga)N-based wurtzite quantum wells following typical device geometries. The small spin-orbit coupling in such nitride materials allows the simultaneous spin polarization of electrons and holes, providing an unexplored path to control spin lasers. For instance, based on microscopic gain calculations[3,4] we found a robust gain asymmetry, one of the key signatures of spin laser operation. In addition, we combine these microscopic gain calculations with phenomenological rate equations to investigate threshold reduction features. We show that the lasing threshold has a nonmonotonic dependence on electron spin polarization, even for a nonvanishing hole spin polarization. The complementary information of these theoretical frameworks provides a powerful predictive materials-specific tool to understand and guide the operation of semiconductor spin lasers.  Holub et al., PRL 98, 146603 (2007); Lindemann et al., APL 108, 042404 (2016); Rudolph et al., APL 82, 4516 (2003); Frougier et al., APL 103, 252402 (2013).  Cheng et al., Nat. Nanotech. 9, 845 (2014).  Faria Junior et al., arXiv:1701.07793 (2017).  Faria Junior et al., PRB 92, 075311 (2015).  Lee et al., APL 105, 042411 (2014).