Analysis of magnetic random telegraph noise in individual arrangements of a small number of coupled MnAs nanoclusters

Abstract

The temporal dependence of the resistance of MnAs nanocluster arrangements grown by selective-area metal-organic vapor-phase epitaxy is investigated at different temperatures. The resistance of such arrangements exhibits random telegraph noise with jumps between discrete resistance levels. The effect is attributed to thermally activated switching of the magnetic domain structure resulting in alterations of spin-dependent scattering between the MnAs clusters of the arrangements. The behavior can be qualitatively understood by a simple model in which it is assumed that the nanocluster arrangement consists of three domains in accordance with investigations by magnetic force microscopy. The magnetizations of the outer larger domains remain fixed, whereas the magnetization of a smaller intermediate domain (or domain wall) exhibits thermally activated switching between local minima of its energy landscape. The results of the model indicate that the time scale of an actual switching event of the entire intermediate domain comprises the nucleation of a seed domain consisting of a few thousand Mn spins followed by the transformation of the entire domain by domain-wall motion in order to reorient its magnetization.