Pressure effect on magnetic transitions in one-dimensional Ca3Co2O6

In Ca₃Co₂O₆ with one-dimensional ferromagnetic Co chains, magnetization measurements have been performed under pressure up to 1.40 GPa. From the temperature and magnetic field dependences of magnetization, we revealed the magnetic phase diagram of Ca₃Co₂O₆. As pressure is applied to the sample, the magnetic ordering temperature T_c1 increases linearly at the similar rate in all fields up to 5.0 T. The spin-flip temperature T_flip and the spin-flip field H_flip show the linear pressure dependence. These results indicate that the lattice compression enhances a nearest-neighbor antiferromagnetic interaction J₁ between chains. By applying pressure, the ferrimagnetic ordering temperature T_c2 increases in 0.5 T, suggesting the enhancement of a second-nearest-neighbor ferromagnetic interaction J₂.