| 1 UNIVERSAL CONDUCTANCE FLUCTUATIONS AND TELEGRAPH NOISE SPECTROSCOPY TO INVESTIGATE THE MAGNETISATION OF SELF ORGANISED ErAs QUANTUM DOTS. (2007) | |||||||||||||
Abstract | |||||||||||||
| Using low temperature magnetotransport techniques we demonstrate that the electrical transport is phase coherent in a GaAs matrix containing self organising ErAs quantum dots and wires of the order of 3 nm diameter. Using telegraph noise spectroscopy we are able to measure the switching of the extremely small magnetic moment (~10-50 B) of an isolated antiferromagnetic cluster of ErAs. Above a critical temperature (T c ~500 mK) the switching is thermally activated. Below this temperature the switching rate saturates and it is the tunnelling of the magnetisation which dominates. The magnetic field dependence of the cross-over temperature (T c) from thermally activated to tunnelling regimes is in good agreement with simple theory for macroscopic quantum tunnelling. 1 | |||||||||||||
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