ACTA

Charge Carrier Dynamics in Ga_1-xMn_xAs Studied by Resistance Noise Spectroscopy

M. Lonsky^a, J. Teschabai-Oglu^a, K. Pierz^b, S. Sievers^b, H.W. Schumacher^b, Y. Yuan^c, R. Böttger^c, S. Zhou^c and J. Müller^a
^aInstitute of Physics, Goethe-University Frankfurt, 60438 Frankfurt (M), Germany
^bPhysikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany
^cHelmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstrasse 400, 01328 Dresden, Germany

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We report on electronic transport measurements of the magnetic semiconductor Ga_1-xMn_xAs, 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.

DOI: 10.12693/APhysPolA.133.520
PACS numbers: 75.50.Pp, 73.50.Td, 73.50.-h, 73.61.-r, 64.60.ah, 61.72.-y