Field induced spin transitions and large magnetoresistance in the quasi-one-dimensional magnet Ca3Co2O6

The Co spin states on trigonal prisms and octahedral were clarified, and the large magnetoresistance during phase transitions induced by externally applied fields was obtained. The magnetic susceptibility of Ca₃Co₂O₆ single crystals were measured for varying temperatures. A second magnetic transition was observed to occur at T_c2=12 K. Results reveal an intra-chain ferromagnetic ordering at T_c1=23 K and a weak antiferromagnetic inter-chain coupling at T_c2=12 K. The field induced phase transition from a ferrimagnetic to ferromagnetic state and the prominent magnetic hysteresis suggests that the sample behaves as an Ising-like antiferromagnetic triangular lattice.