Quantum Kinetic Anatomy of Electron Angular Momenta Edge Accumulation

Abstract: Controlling electron's spin and orbital degrees of freedom has been a major research focus over the past two decades, as it underpins the electrical manipulation of magnetization. Leveraging a recently introduced quantum kinetic theory of multiband systems [T. Valet and R. Raimondi, Phys. Rev. B 111, L041118 (2025)], we outline how the intrinsic angular momenta linear response is partitioned into intraband and interband contributions. Focusing on time reversal and inversion symmetric metals, we show that the spin and orbital Hall currents are purely intraband. We also reveal that the edge densities originate partially, and in the orbital case mostly, from a new interband mechanism. We discuss how this profoundly impacts the interpretation of orbital edge accumulation observations, and has broader implications for our understanding of current induced torques.