Temperature dependent diamagnetic-paramagnetic transitions in metal/semiconductor quantum rings

Abstract

We present theoretical studies of temperature dependent diamagnetic-paramagnetic transitions in thin quantum rings. Our studies show that the magnetic susceptibility of metal/semiconductor rings can exhibit multiple sign flips at intermediate and high temperatures depending on the number of conduction electrons in the ring ($N$) and whether or not spin effects are included. When the temperature is increased from absolute zero, the susceptibility begins to flip sign above a characteristic temperature that scales inversely with the number of electrons according to $N^{-1}$ or $N^{-1/2}$, depending on the presence of spin effects and the value of $N\mathrm{mod}4$. Analytical results are derived for the susceptibility in the low and high temperature limits, explicitly showing the spin effects on the ring Curie constant.

References in corpus (6)

• Persistent currents in normal metal rings
• Spin-like susceptibility of metallic and insulating thin films at low temperature
• Persistent currents in one dimension: the other side of Leggett's theorem
• Current-flux characteristics in mesoscopic nonsuperconducting rings
• Diamagnetism of metallic nanoparticles as the result of strong spin-orbit interaction
• Equilibrium properties of mesoscopic quantum conductors