Magnetic quantum tunneling in Ca3Co2O6 studied by ac susceptibility: Temperature and magnetic-field dependence of the spin-relaxation time

Overview & Synopsis

The geometrically frustrated spin-chain compound Ca3Co 2O6 was recently found to exhibit properties suggesting the phenomenon of quantum tunneling of the magnetization (QTM). The present paper addresses this issue by investigating the temperature and magnetic-field dependence of the characteristic spin-relaxation time τ. This study is based on the analysis of the out-of-phase ac magnetic susceptibility of single crystals. The overall behavior is found to support the occurrence of QTM in Ca3Co2O6: (i) saturation of τ at low T; (ii) observation of identical τ values in the magnetic fields corresponding to the steps in the M vs H curve at low T; (iii) existence of a dip centered at zero field in the τ vs H curve at low T. These QTM-like features found in Ca3Co2O6 are compared to those previously reported in other materials such as single-molecular magnets.