Pressure Effect on the Magnetic Transition Temperatures in the Intermetallic Compounds Mn₃MC (M=Ga, Zn and Sn)

The pressure effect on the magnetic transition temperatures of Mn 3 GaC, Mn 3 ZnC and Mn 3 SnC were measured under pressures up to 13 kbar. The pressure derivatives of the transition temperatures are obtained to be d T t /d P =-3.5 K/kbar and d T C /d P =0.4 K/kbar for Mn 3 GaC, d T t /d P =-0.9 K/kbar and T C /d P =0 for Mn 3 ZnC and d T C /d P =-1.9 K/kbar for Mn 3 SnC, where T t and T C are the magnetic order-order transition temperature and the Curie temperature, respectively. An intermediate magnetic phase (I) is induced in Mn 3 GaC under pressures above 3 kbar. The triple point (Antiferro./I/Ferro.) was determined to be T c =158 K and P c =3 kbar. The temperature variations of magnetization, magnetic susceptibility and latlice parameter were also measured.