Spin-glass-like behavior of Ge:Mn
Abstract
We present a detailed study of the magnetic properties of low-temperature-molecular-beam-epitaxy grown Ge:Mn dilute magnetic semiconductor films. We find strong indications for a frozen state of Ge_{1-x}Mn_{x}, with freezing temperatures of T_f=12K and T_f=15K for samples with x=0.04 and x=0.2, respectively, determined from the difference between field-cooled and zero-field-cooled magnetization. For Ge_{0.96}Mn_{0.04}, ac susceptibility measurements show a peak around T_f, with the peak position T'_f shifting as a function of the driving frequency f by Delta T_f' / [T_f' Delta log f] ~ 0.06, whereas for sample Ge_{0.8}Mn_{0.2} a more complicated behavior is observed. Furthermore, both samples exhibit relaxation effects of the magnetization after switching the magnitude of the external magnetic field below T_f which are in qualitative agreement with the field- and zero-field-cooled magnetization measurements. These findings consistently show that Ge:Mn exhibits a frozen magnetic state at low temperatures and that it is not a conventional ferromagnet.
Keywords
Cite
@article{arxiv.cond-mat/0604041,
title = {Spin-glass-like behavior of Ge:Mn},
author = {C. Jaeger and C. Bihler and T. Vallaitis and S. T. B. Goennenwein and M. Opel and R. Gross and M. S. Brandt},
journal= {arXiv preprint arXiv:cond-mat/0604041},
year = {2007}
}
Comments
Revised version contains extended interpretation of experimental data