Quantum-Uncertainty-Governed Spin Dynamics in s-d Coupled Systems

Abstract: We investigate quantum fluctuation effects arising from the Heisenberg uncertainty principle governing angular momentum operators in the full dynamical evolution of disentanglement-entanglement-disentanglement between itinerant electrons and localized magnetic moments under the s-d exchange interaction. Beyond the conventional deterministic spin-transfer torque, we identify an intrinsic channel for the transfer of spin quantum fluctuations. By extending the Landau-Lifshitz-Gilbert equation to include both quantum and thermal stochastic fields, we reveal a temperature regime where quantum fluctuations dominate spin dynamics. Furthermore, voltage-controlled magnetic anisotropy can exponentially amplify these quantum fluctuation signals, enabling their binary detection via tunneling magnetoresistance in magnetic tunnel junctions. These results establish a microscopic framework for quantum fluctuation-driven spin dynamics and provide a fundamental route toward spin-based quantum true random number generation.