Charge Carrier Dynamic in Ga1-xMnxAs Studied by Resistance Noise Spectroscopy


Charge Carrier Dynamic in Ga1-xMnxAs Studied by Resistance Noise Spectroscopy

Lonsky, M.; Teschabai–Oglu, J.; Pierz, K.; Sievers, S.; Schumacher, H. W.; Yuan, Y.; Böttger, R.; Zhou, S.; Müller, J.

We report on electronic transport measurements of the magnetic semiconductor Ga1-xMnxAs, whereby the defect landscape in various metallic thin films (x = 6%) was tuned by He-ion irradiation. Changes in the distribution of activation energies, which strongly determine the low-frequency 1/f-type resistance noise characteristics, were observed after irradiation and can be explained by deep-level traps residing in the As sublattice. Various other kinds of crystalline defects such as, for instance, Mn interstitials, which possibly form nanoscale magnetic clusters with a fluctuating spin orientation, also contribute to the 1/f noise and can give rise to random telegraph signals, which were observed in films with x = 7%. In addition, we neither find evidence for a magnetic polaron percolation nor any features in the noise near the Curie temperature.

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Publ.-Id: 27295