Anharmonic Phonon Effects on Spin Dynamics in Solids

Applications in spintronics and quantum information technology require materials with long lived spin states at finite temperatures. First-principles methodologies based on Lindbladian dynamics predict spin lifetimes in materials, including electron-phonon and electron-impurity scattering for materials. However, the harmonic approximation is often used for analyzing lattice dynamics and spin-phonon coupling in materials, which breaks down for materials which exhibit strong anharmonic effects. In this work, we combine first-principles density matrix dynamics techniques with temperature-dependent effective potential approaches to incorporate anharmonic contributions to the phonons, enabling prediction of finite temperature phonon effects on spin lifetimes. Using this approach, phonon softening can be observed, and phonon-dependent properties can be predicted in materials which would appear to be dynamically unstable at zero temperature. We perform first principles prediction of temperature and electromagnetic field dependence of spin lifetimes in a variety of materials from semiconductors to 2D perovskites.