Temperature scales of magnetization oscillations in an asymmetric quantum dot

The temperature scales of different types of magnetization oscillations in a quantum dot, formed in a two-dimensional electron gas by circularly symmetric or asymmetric confining potentials, are studied. Aharonov-Bohm (AB) oscillations, with a superimposed fine structure caused by magnetic-field-induced shifts of the electronic energy levels, develop at low magnetic fields ${\omega }_c\ll {\omega }_{x,y}$ (where ${\omega }_c$ is the cyclotron frequency and ${\omega }_{x,y}$ are the harmonic confining frequencies that determine the shape and effective size of the dot). The characteristic scale of the fine-structure fluctuations is ${\phi }_0/({\varepsilon }_F/ħ{\omega }_0)$ (where ${\phi }_0$ is the flux quantum, ${\varepsilon }_F$ is the Fermi energy, and ${\omega }_0=\sqrt{{\omega }_x{\omega }_y})$ and they are smeared at temperatures $T>(ħ{\omega }_0{)}^2/{\varepsilon }_F,$ with restoration of the pure AB picture for $T<~ħ{\omega }_0.$ At high magnetic fields, ${\omega }_c\gg {\omega }_{x,y},$ de Haas–van Alphen oscillations develop (for $T<~ħ{\omega }_c),$ with a superimposed AB oscillatory structure which undergoes temperature smearing for $T>~ħ{\omega }_0({\omega }_0/{\omega }_c).\mathrm{}$ Effects of the asymmetry of the confining potential on the magnetization oscillations are discussed. The magnetic moment of the dot as a function of the chemical potential exhibits a series of paramagnetic peaks superimposed on a diamagnetic background, and the influence of the magnetic-field strength and asymmetry of the dot on these features is discussed.