Uncover the magneto-structural coupling in the MnCoGe-based magnetocaloric alloys

Our recent results show that including 1 at.% of boron atoms in the MnCoGe alloy can make the otherwise separated ferromagnetic and orthorhombic-hexagonal structural transitions coincide, i.e. the realization of a magneto-structural transition. This leads to a giant magnetocaloric effect. However, the coupling mechanism of the magnetic and structural transitions is still not clear. Magnetic measurements suggest partial quenching of sublattice magnetic moments during the structural transition. We have solved the magnetic structure of the orthorhombic phase using neutron diffraction. Here we propose to perform neutron diffraction on the hexagonal MnCoGe phase. This work will allow us to elucidate the roles of the Mn and Co moments in the magneto-structural transition as well as the interplay between the magnetic and structural transition in the MnCoGe-based magnetocaloric materials.