Landolt-Börnstein - Group III Condensed Matter

10.2 Finite temperature


This chapter contains literature on quantized conductance and finite temperature of connected rings. Finite temperature leads to energy evaraging of AB interference patterns. Within some band width, Ec, the neighbouring levels are spatially correlated and for k B T < Ec, only the fundamental AB interference pattern contributes to the conductance. Magnetoresistance (MR) data of GaAs ring at T = 0.45K, 0.75K, 1.7K, and 4.2K are shown. In the Fourier transform of the data at 0.75K, peaks corresponding to h/e and h/2e oscillations were present. The Fourier periods were independent of temperature. The temperature dependence of the amplitude of the AB oscillations is illustrated. The values of the phase coherence length as a function of temperature were extracted and results are shown. MR data for a 7.8 μm perimeter ring of GaAs and a 5.2 μm perimeter ring of GaInAs at different temperatures are shown. The AB oscillations had the expected h/e period. The phase coherence length in the pseudomorphic GaInAs rings seemed to be longer than in the other samples as AB oscillations were observable up to 19K in comparison with 4K in the GaAs rings. The AB conductance amplitude as a function of temperature for four different rings of GaAs is illustrated. The amplitudes of the AB oscillations were smaller for rings with a larger perimeter and decreased with increasing temperature. The four-terminal MR of an In0.77Ga0.23As/InP ring as a function of magnetic field at 330mK is also shown.

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10.2 Finite temperature
Book Title
Electronic Transport. Part 1: Quantum Point Contacts and Quantum Wires
10 Connected rings
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Landolt-Börnstein - Group III Condensed Matter
  • B. Kramer
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  • A. Fechner
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