Publications in Scientific Journals:

S. Khmelevskyi, A.V. Ruban, P. Mohn:
"Magnetic ordering and exchange interactions in structural modifications of Mn3Ga alloys: interplay of frustration, atomic order and offstoichiometry";
Physical Review B, 93 (2016), 1844041 - 1844049.

English abstract:
Mn-Ga alloys close to the Mn
Ga stoichiometry can be synthesized in three different crystal modifications:
hexagonal, tetragonal, and face-centered cubic, both in bulk and in thin-film forms. The magnetic ordering of
these modifications is varying from noncollinear antiferromagnetic in the hexagonal case to ferrimagnetic order in
the tetragonal one, whereas it is still unknown for the atomically disordered fcc structure. Here we study the onset
of magnetic order at finite temperatures in these systems on a first-principles basis calculating the interatomic
magnetic exchange interactions in the high-temperature paramagnetic regime. We employ the disordered local
moment formalism and the magnetic force theorem within the framework of the local spin-density approximation
and Monte Carlo simulations taking also the effects of atomic disorder in fcc alloys into account. In particular we
find the origin of the stabilization of the noncollinear 3
structure in competition between antiferromagnetic inter-
and in-plane couplings of frustrated kagome planes in hexagonal Mn
Ga and predict the antiferromagnetic-1
collinear order due to frustration in fcc alloys. Special attention is paid to the effects of the off-stoichiometry
and the consequences of atomic disorder. We calculate the site-preference energy of Ga antisite atoms in the
tetragonal structures in the range of the compositions from Mn
Ga to Mn
Ga and slightly beyond and confirm
the earlier explanation of the effect of magnetization increase due to Ga preferentially occupying one of the Mn

Created from the Publication Database of the Vienna University of Technology.