Prediction of extremely long mobile electron spin lifetimes at room temperature in low-Z wurtzite semiconductor quantum wells

Many proposed spintronics devices require mobile electrons at room temperature with very long spin lifetimes. One route to achieving this is to use quantum wells with tunable spin-orbit (SO) parameters. Research has focused on materials with the zincblende structure such as GaAs, which however, do not have long spin lifetimes at room temperature. We show that low-Z materials with the wurtzite structure are much better suited for spintronics applications. Their hexagonal symmetry implies that SO couplings can be completely canceled over a very wide range of electron momenta at zero temperature. Low-Z materials possess smaller SO couplings resulting in long spin lifetimes at room temperature. This leads to predictions of spin lifetimes exceeding 2 ms at helium temperatures in wurtzite AlN and, most relevant to spintronic devices, spin lifetimes up to 0.5 $\mu s$ are predicted for tuned AlN wells at room temperature.