Magnetovolume effect in Mn3Cu1-xGexN related to the magnetic structure: Neutron powder diffraction measurements

Magnetic structures in an antiperovskite system, Mn3Cu1-xGexN, with a large magnetovolume effect above x=0.15 have been studied by neutron powder diffraction measurement. The present neutron study revealed that not only a cubic crystal structure but also a Gamma(5g) antiferromagnetic spin structure are key ingredients of the large magnetovolume effect in this itinerant electron system. The large magnetovolume effect is possibly ascribed to the geometrical frustration originating from the corner-shared octahedra of the antiperovskite structure.