Close correlation among lattice, spin, and charge in the manganese-based antiperovskite material

The temperature (T)-dependent magnetization, transport, and magnetoresistance (MR) properties of a Mn-based compound GaCMn3 that has the antiperovskite structure were studied using neutron powder diffraction and SQUID measurements. With decreasing T, the magnetic phase transitions from a paramagnetic to an antiferromagnetic (AFM) state via an intermediate ferromagnetic (FM) phase are observed in this material. These magnetic transitions and their corresponding resistivity slopes dρ/dT are strongly correlated with linear thermal expansion coefficients of the lattice parameter a−1(da/dT). A large negative MR of 50% even at 0.3 T is seen near the phase boundary between the FM and AFM states.