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Electronic phase separation in insulating (Ga,Mn)As with low compensation: Super-paramagnetism and hopping conduction.

Author
Abstract
:

In the present work, low compensated insulating (Ga,Mn)As with 0.66% Mn is obtained by ion implantation combined with pulsed laser melting. The sample shows variable-range hopping transport behavior with a Coulomb gap in the vicinity of the Fermi energy, and the activation energy is reduced by an external magnetic field through suppression of scattering between holes and randomly orientated ferromagnetic grains. A blocking super-paramagnetism is observed rather than ferromagnetism. Below the blocking temperature, the sample exhibits a colossal negative magnetoresistance. Our studies confirm that the disorder-induced electronic phase separation occurs in (Ga,Mn)As samples with a Mn concentration in the insulator-metal transition regime, and it can account for the observed superparamagnetism and the colossal magnetoresistance.

Year of Publication
:
2018
Journal
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Journal of physics. Condensed matter : an Institute of Physics journal
Date Published
:
2018
ISSN Number
:
0953-8984
URL
:
https://doi.org/10.1088/1361-648X/aaa9a7
DOI
:
10.1088/1361-648X/aaa9a7
Short Title
:
J Phys Condens Matter
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