X-ray Powder Diffraction Studies of Mn3Ga0.97Al0.03C in Magnetic Fields

We have performed the X-ray powder diffraction measurements for Mn3Ga0.97Al0.03C with a perovskite-type structure in the temperature range from 8 to 320 K in magnetic fields up to 5 T, in order to investigate the structural properties affected by the magnetic field. The compound has a successive magnetic phase transition below 160 K: the ferromagnetic (F)–intermediate (I)–antiferromagnetic (AF) phases for cooling process. The lattice parameter a abruptly increases by 0.23%, accompanied by the transition from the I to AF phases at TAF–I=130 K. In addition, we clearly observed that magnetic field induces the I phase with small a and suppresses the AF phase with large a below TAF–I.