Magneto-Elastic Coupling in a Sinusoidal Modulated Magnet Cr_2GaN

We use neutron powder diffraction to investigate the magnetic and crystalline structure of Cr_2GaN. A magnetic phase transition is identified at T \approx 170 K, whereas no trace of structural transition is observed down to 6 K. Combining Rietveld refinement with irreducible representations, the spin configuration of Cr ions in Cr_2GaN is depicted as an incommensurate sinusoidal modulated structure characterized by a propagating vector k=(0.365, 0.365, 0). Upon warming up to the paramagnetic state, the magnetic order parameter closely resembles to the temperature dependence of c-axis lattice parameter, suggesting strong magneto-elastic coupling in this compound. Therefore, Cr_2GaN provides a potential platform for exploration of magnetically tuned properties such as magnetoelectric, magnetostrictive and magnetocaloric effects, as well as their applications.