Spin-Canting-Controlled Hole Spin Relaxation in Two-Dimensional Magnet CrSBr

Control of spin dynamics is a central challenge for nanoscale spintronics and quantum technologies. Here we use interlayer spin-canting angles (as a proxy for magnetic-field-induced spin reorientation) to probe hole spin relaxation in CrSBr. Noncollinear time-dependent density functional theory combined with nonadiabatic molecular dynamics reveals that hole energy relaxation follows 90° > 60° ≈ 0° > 30° due to the decreased nonadiabatic coupling. The θ = 0° case is a special case, where thermally induced near-degeneracies sustain additional coupling. Spin relaxation exhibits a distinct mechanistic transition: θ = 0° shows ultrafast depolarization dominated by adiabatic spin flips, while finite θ configurations relax through nonadiabatic spin flips with times comparable to or exceeding energy relaxation. The θ = 90° state flips fastest among the canted cases due to the aligned spin character of its top valence bands. These results elucidate how the magnetic-field-controlled spin orientation governs ultrafast spin dynamics in magnets.