Mechanism of magnetostructural transformation in multifunctional Mn3GaC

E. T. Dias,1 K. R. Priolkar,1 Rajeev Ranjan,2 A. K. Nigam,3 and S. Emura4

(Dated: October 1, 2018)

Abstract 

Mn3GaC undergoes a ferromagnetic to antiferromagnetic, volume discontinuous cubic-cubic phase transition as a function of temperature, pressure and magnetic field. Through a series of temperature dependent x-ray absorption fine structure spectroscopy experiments at the Mn K and Ga K edge, it is shown that the first order magnetic transformation in Mn3GaC is entirely due to distortions in Mn sub-lattice and with a very little role for Mn-C interactions. The distortion in Mn sub-lattice results in long and short Mn-Mn bonds with the longer Mn-Mn bonds favoring ferromagnetic interactions and the shorter Mn-Mn bonds favoring antiferromagnetic interactions. At the first order transition, the shorter Mn-Mn bonds exhibit an abrupt decrease in their length resulting in an antiferromagnetic ground state and a strained lattice.

https://arxiv.org/pdf/1708.09554.pdf

The inset shows a schematic of the unit cell and the two magnetic interactions denoted by J1 and J2 believed to be responsible for magnetic transitions in Mn3GaC.