TY  - JOUR
AU  - Picozzi, S.
AU  - Lezaic, M.
TI  - Ab-initio study of exchange constants and electronic structure in diluted magnetic group-IV  semiconductors
JO  - New journal of physics
VL  - 10
SN  - 1367-2630
CY  - [Bad Honnef]
PB  - Dt. Physikalische Ges.
M1  - PreJuSER-62272
SP  - 055017
PY  - 2008
N1  - Record converted from VDB: 12.11.2012
AB  - Exchange-constants have been evaluated from first-principles in Mn-doped Ge, mainly focusing on the effects of the impurity concentration and of the arrangement of Mn-atoms in the semiconducting matrix. As expected, the Mn-concentration strongly affects the magnitude of the exchange constants (especially between Mn as first-nearest-neighbors (NNs) in the cation position). Interestingly, the arrangement of Mn atoms is found to be relevant for the behavior of the second-NN exchange-constant along the [110]-bonding direction, which shows either a strongly ferromagnetic or a marked antiferromagnetic behavior, depending on whether the interaction is mediated by a Ge or by an Mn atom, respectively. This suggests that, at least for rather high values of the doping concentration (similar to 10%), a detailed knowledge of the Mn positions in the host is required for a careful prediction of the exchange constants and, therefore, of the ordering Curie temperature in Mn-doped Ge. The analysis of the impurity-and host-induced effects on the exchange constants is carried out by comparing (i) Mn- and Cr-doped Ge and (ii) Mn-doped Ge and GaAs. Our findings regarding the global weak antiferromagnetism for CrGe confirm that ferromagnetism in diluted magnetic semiconductors requires the presence of holes, whereas Ge and GaAs appear rather similar as for the exchange constants, both showing strong environmental effects.
KW  - J (WoSType)
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000256426800013
DO  - DOI:10.1088/1367-2630/10/5/055017
UR  - https://juser.fz-juelich.de/record/62272
ER  -