Magnetic-field dependence of spin-phonon relaxation and dephasing due to g-factor fluctuations from first principles

TL;DR

This study uses first-principles simulations to analyze how magnetic fields influence electron spin relaxation and dephasing in materials, highlighting the role of g-factor fluctuations in spin dynamics.

Contribution

It introduces a first-principles simulation approach to directly predict spin lifetimes and disentangle dephasing from decoherence in materials like CsPbBr3 and silicon.

Findings

g-factor fluctuations cause complex magnetic field dependence of spin lifetimes

Off-diagonal g-tensor components significantly affect T1 in silicon

Anisotropic g-factors influence spin dynamics even in low spin-orbit materials

Abstract

The electron spin decay lifetime in materials can be characterized by relaxation (T1) and irreversible (T2) and reversible (T2*) decoherence processes. Their interplay leads to a complex dependence of spin relaxation times on the direction and magnitude of magnetic fields, 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 non-trivial 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.