We introduce a tight-binding theory of spin-correlated dissipationless circulating currents in 2D systems. In host materials with strong spin-orbit coupling, the unquenching of the orbital angular momentum gives rise to finite ground state current densities induced by paramagnetic spin states. In contrast to the spin part, the orbital magnetic moment is still surprisingly not well understood. Here we use our real-space formalism of the discrete current operator to elucidate spatial anisotropies of the short-range orbital magnetic moments impacting spin-spin coupling, g-tensors and hyperfine interaction calculations of defects. The shape and spatial extent of these dissipationless circulating currents are greatly affected by the spatial symmetry of the spin-orbit fields, offering significant opportunities for manipulating nanoscale magnetic fields and coupling magnetic defects through electric gate control. Furthermore, the fringing magnetic field emerging from the current can provide a direct way to measure the spin-orbit fields of the host, as well as the defect spin orientation, through scanning nanoscale magnetometry.
The combination of spin-orbit coupling with broken spatial inversion symmetry in semiconductors (e.g. zinc-blende quantum-wells and surfaces) and localized spin states originated from a single magnetic defect is a promising system to realize future semiconductor spintronics devices [1].
We present a theory of dissipationless circulating current induced by a magnetic defect in a two-dimensional electron gas with both Bychkov-Rashba and Dresselhaus spin-orbit coupling [1]. The shape and spatial extent of these dissipationless circulating currents depend dramatically on the relative strengths of spin-orbit fields with differing spatial symmetry, offering the potential to use an electric gate to manipulate nanoscale magnetic fields and couple magnetic defects. The spatial structure of the fringing magnetic field emerging from the current is calculated and provides a direct way to measure the spin-orbit fields of the host, as well as the defect spin orientation, through scanning nanoscale magnetometry [3].
[1] Wolfowicz, G., Heremans, F.J., Anderson, C.P. et al. Nat RevMater 6, 906–925 (2021).
[2] Da Cruz, A.R. and Flatté, M. E., arXiv:2111.06770
[3] Casola, F. and van der Sar, T. and Yacoby, A. Nature Reviews Materials, 3 (1), 17088 (2018).
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