Orbital and spin contributions to the $g$-tensors in metal nanoparticles

Abstract

We present a theoretical study of the mesoscopic fluctuations of $g$-tensors in a metal nanoparticle. The calculations were performed using a semi-realistic tight-binding model, which contains both spin and orbital contributions to the $g$-tensors. The results depend on the product of the spin-orbit scattering time ${\tau }_{\text{so}}$ and the mean-level spacing $\delta$, but are otherwise weakly affected by the specific shape of a {\it generic} nanoparticle. We find that the spin contribution to the $g$-tensors agrees with Random Matrix Theory (RMT) predictions. On the other hand, in the strong spin-orbit coupling limit $\delta {\tau }_{\text{so}}/\hslash \to 0$, the orbital contribution depends crucially on the space character of the quasi-particle wavefunctions: it levels off at a small value for states of $d$ character but is strongly enhanced for states of $sp$ character. Our numerical results demonstrate that when orbital coupling to the field is included, RMT predictions overestimate the typical $g$-factor of orbitals that have dominant $d$-character. This finding points to a possible source of the puzzling discrepancy between theory and experiment.

arXiv comment21 pages, 6 figures; accepted for publication in Physical Review B

References in corpus (9)

• Coupling of Nonlocal Potentials to Electromagnetic Fields
• The g-factors of discrete levels in nanoparticles
• Fluctuating spin g-tensor in small metal grains
• Studies of spin-orbit scattering in noble-metal nanoparticles using energy level tunneling spectroscopy
• Effects of Spin-Orbit Interactions on Tunneling via Discrete Energy Levels in Metal Nanoparticles
• Magnetization orientation dependence of the quasiparticle spectrum and hysteresis in ferromagnetic metal nanoparticles
• Measurements of strongly-anisotropic g-factors for spins in single quantum states
• Magnetic-field dependence of energy levels in ultrasmall metal grains
• Fine Structure in Energy Spectra of Ultrasmall Au Nanoparticles

Cited by in corpus (9)

• Electron correlations in metal nanoparticles with spin-orbit scattering
• Spatial non-adiabatic passage using geometric phases
• Elementary transitions and magnetic correlations in two-dimensional disordered nanoparticle ensembles
• Universal non-adiabatic geometric manipulation of pseudo-spin charge qubits
• Anisotropy in Ferromagnetic Nanoparticles: Level-to-Level Fluctuations of a Collective Effect
• Magnetic Anisotropy of Isolated Cobalt Nanoplatelets
• Magnetic response of energy levels of superconducting nanoparticles with spin-orbit scattering
• Spin-orbit scattering in superconducting nanoparticles
• Universal Non-adiabatic Holonomic Gates in Quantum Dots and Single-Molecule Magnets