Temperature scales of magnetization oscillations in an asymmetric quantum dot - art. no. 115323

The temperature scales of different types of magnetization oscillations in a:quantum dot, formed in a two-dimensional electron gas by circularly symme tric or asymmetric confining potentials, are studied. Aharonov-Bohm (AB) os cillations, with a superimposed fine structure caused by magnetic-field-ind uced shifts of the electronic energy levels, develop at low magnetic fields omega (c) << omega (x,y) (where omega (c) is the cyclotron frequency and o mega (x,y) are the harmonic confining frequencies that determine the shape and effective size of the dot). The characteristic scale of the fine-struct ure fluctuations is phi (0)/(epsilon (F)/(h) over bar omega (0)) (where phi (0) is the flux quantum, epsilon (F) is the Fermi energy, and omega (0) = root omega (x)omega (y)) and they are smeared at temperatures T>((h) over b ar omega (o))(2)/epsilon (F), with restoration of the oo pure AB picture fo r T less than or equal to(h) over bar omega (0). At high magnetic fields, o mega (c)>>omega (x,y) de Haas-van Alphen oscillations develop (for T less t han or equal to(h) over bar omega (c)), with a superimposed AB oscillatory structure which undergoes temperature smearing for T greater than or equal to(h) over bar omega (0)(omega (0)/omega (c)). Effects of the asymmetry of the confining potential on the magnetization oscillations are discussed. Th e magnetic moment of the dot as a function of the chemical potential exhibi ts 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.