First-principles spin decoherence predictions published in Phys. Rev. B
J. Quinton, M. Fadel, J. Xu, A. Habib, M. Chandra, Y. Ping and R. Sundararaman, “Magnetic-field dependence of spin-phonon relaxation and dephasing due to -factor fluctuations from first principles”, Phys. Rev. B 111, 115113 (2025)
The electron spin decay lifetime in materials can be characterized by relaxation (T1) and irreversible (T2) and reversible (T1*) decoherence processes. Their interplay leads to a complex dependence of spin lifetimes on the direction and magnitude of magnetic fields, which is relevant for spintronics and quantum information applications. Here, we use real-time first-principles density matrix dynamics simulations to directly simulate Hahn echo measurements, disentangle dephasing from decoherence, and predict T1, T2, and T2* spin lifetimes. We show that g-factor fluctuations lead to nontrivial magnetic field dependence of each of these lifetimes in inversion-symmetric crystals of CsPbBr3 and silicon, even when only intrinsic spin-phonon scattering is present. Most importantly, fluctuations in the off-diagonal components of the g tensor lead to a strong magnetic-field dependence of even the T1 lifetime in silicon. Our calculations elucidate the detailed role of anisotropic g factors in determining the spin dynamics even in simple, low spin-orbit coupling materials such as silicon.