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[1], there is a recent exception using nitride-based compounds with wurtzite structure[2], 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[3]. 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[5] 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. [1] 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). [2] Cheng et al., Nat. Nanotech. 9, 845 (2014). [3] Faria Junior et al., arXiv:1701.07793 (2017). [4] Faria Junior et al., PRB 92, 075311 (2015). [5] Lee et al., APL 105, 042411 (2014).
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