Manipulation of the magnetic properties in Er1−xCo2 compounds by atomic vacancies

ErCo2 compound is a well-known magnetocaloric material which shows giant magnetocaloric effect in the vicinity of first-order phase transition. We demonstrate a new way of fine tuning its crystal structure and magnetic properties. Er atomic vacancies are introduced in order to manipulate the local atomic environment, the phase transition characteristics, and the magnetocaloric effect as well. Er1−xCo2 can be stable over a narrow homogenous range, and maintain the cubic structure. The Bragg peaks shift upward to higher angles, and the unit cell volume contracts with reduction of the Er content. The Curie temperatures in low magnetic field increase from 32 K (ErCo2) to 46 K (Er0.97Co2), and linearly change with the magnetic field in nearly same slope. Er1−xCo2 compounds exhibit anomalous susceptibility behaviors in the paramagnetic state, and deviate from the Curie-Weiss law at around 100 K. The temperature range of anomalous susceptibility behaviors also move upward to higher temperature with reduction of Er content. Er1−xCo2 compounds also show anomalous coercivity behavior in the vicinity of phase transition. Er1−xCo2 compounds exhibit large magnetocaloric effect and good refrigerant capacity in the vicinity of ferrimagnetic-paramagnetic phase transition.