Magnetic phase diagram of frustrated triangular-lattice system Ca3Co2O6Ca3Co2O6

In order to clarify the magnetism and the spin dynamics of Ca3Co2O6Ca3Co2O6, which is known as a frustrated system of the antiferromagnetic triangular lattice consisting of Ising spins, we have performed magnetization, specific heat and muon spin relaxation (μSR)(μSR) measurement. Longitudinal-field μSRμSR measurement clarifies that the internal magnetic field at the muon site is fluctuating at 20 K, which is between the magnetic transition temperature Tc1∼25K and the spin freezing temperature Tc2∼12K. From the analysis of the longitudinal relaxation time, we found the existence of the phase boundary at around H0H0 (∼4kOe at 20 K). H0H0 separates two magnetic phases, that is, partially disordered antiferromagnetic phase below H0H0 and dynamical ferrimagnetic phase above H0H0. We propose the magnetic phase diagram of Ca3Co2O6Ca3Co2O6.