[Back]

S. Khmelevskyi, E. Simon, L. Szunyogh, P. Mohn:
"Microscopic origin of ferro-antiferromagnetic transition uponnon-magnetic substitution in Ru₂(Mn_1-x V_x)Ge full Heusler alloys";
Journal of Alloys and Compounds, 692 (2017), 178 - 182.

On the basis of first-principle simulations of interatomic magnetic exchange interactions, we show that
the transition from antiferromagnetic order in Ru2MnGe to ferromagnetic order in vanadium substituted
Ru2Mn1 xVxGe is due to a progressive increase of the first-nearest neighbor (NN) ferromagnetic coupling
between Mn atoms. The revealed mechanism is quite unusual since commonly one would expect, and
indeed it has been proposed earlier, that the transition scenario is due to the suppression of some
relevant interactions by the non-magnetic substitution or chemical disorder effects. Here, using our abinitio
calculated exchange parameters and performing finite temperature Monte Carlo statistical simulations
on a disordered lattice, we describe the experimental magnetic phase diagram for the full range of
vanadium concentrations, including the variation of the ordering temperature and the onset of finite
magnetization in the ground state. Since the observed changes in the MneMn magnetic interactions are
continuous with increasing V content, we argue that there is a threshold concentration of V substitutions
where the critical fluctuations associated with frustration effects on the fcc lattice could be studied
experimentally.

Magnetic phase transitions Exchange interactions Alloying effects First-principle simulations