Abstract
Magnetotransport in submicron devices formed on the basis of GaAs/AlGaAs structures is simulated by the method of nonequilibrium Green functions. In the one-particle approximation, the influence of a perpendicular magnetic field on electron transmission through a quasi-one-dimensional quantum dot and the Aharonov—Bohm interferometer is considered. Two-terminal conductance and magnetic moment of the devices are calculated. Two-dimensional patterns of equilibrium (persistent) currents are obtained. The correlations between energy dependences of magnetic moment and conductance are considered. For the quasi-one-dimensional quantum dot, regular conductance oscillations similar to the ABOs were found at low magnetic fields (0.05—0.4 T). In the case of a ring interferometer, the contribution to the total equilibrium current and magnetic moment at a given energy can change sharply both in magnitude and in sign when the magnetic field changes within the same Aharonov—Bohm oscillation. The conductance through the interferometer is determined not by the number of propagating modes, but rather by the influence of triangular quantum dots at the entrances to the ring, causing back scattering. Period of calculated ABOs corresponds to that measured for these devices.
Highlights
Magnetotransport in submicron devices formed on the basis of GaAs/AlGaAs structures is simulated by the method of nonequilibrium Green functions
For the quasi−one−dimensional quantum dot, regular conductance oscillations similar to the ABOs were found at low magnetic fields (0.05—0.4 T)
A., Groth S., Grundler D., Heyn Ch., Heitmann D
Summary
Полный равновесный ток для заданных значений энергии Ферми EF и B определяется суммой вкладов dJ(x,y)/dE по состояниям с энергиями E ≤ EF. Затем по найденному U(x,y) и заданному B определялись полный неравновесный ток I через устройство при заданных EF и тянущем напряжении V (кондактанс G = I/V) [7, 12,13,14]. Что периоду магнитополевых осцилляций соответствует эффективная площадь S = Φ0/∆B, которая немного меньше площади квантовой точки. Это относится не только к расчетному ∆B = 19 мТл, что показано пунктирным овалом на рис. Основной ток течет в резервуарах и по широкому кольцу на периферии квантовой точки. 1. Вычисленные магнитополевые характеристики квазиодномерной для квазиодномерной квантовой точквантовой точки при EF = 0,1 мэВ: зависимости кондактанса и производной магнитного момента dM/dE от B.
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