Charge redistribution at the magnetostructural transition in MnCoGe alloys measured by high-resolution powder diffraction

The giant magnetocaloric effect that couples a change in magnetic field to a change in temperature has been observed in several materials showing either a magnetoelastic or a magnetostructural transition. In the magnetoelastic transition the symmetry of the lattice is conserved, while it changes in the magnetostructural transition. Density functional theory (DFT) calculations suggest that the underlying mechanisms of the magnetoelastic and magnetostructural transitions both rely on an electronic redistribution. We have successfully confirmed this prediction for the magnetoelastic transition by powder X-ray diffraction. To test the generality of the predicted mechanism, we propose to perform high-resolution powder X-ray diffraction on MnCoGe-based alloys that show a magnetostructural transition. Three-dimensional charge-density plots for various temperatures will be used to evaluate the charge redistribution across the transition.