Large magnetocaloric effect and magnetoresistance in ErNi single crystal

Abstract The magnetic properties, magnetocaloric effect and magnetoresistance in ErNi single crystal have been investigated in detail. With decreasing temperature, ErNi single crystal undergoes two successive magnetic transitions: a paramagnetic to ferromagnetic transition at TC =11 K and a spin-reorientation transition at TSR =5 K. Meanwhile, a sharp field-induced metamagnetic transition is observed below the TC along the a axis. ErNi single crystal possesses a giant magnetocaloric effect around TC. The maximum magnetic entropy change is -36.1 J (kg K)-1 along the a axis under the field change of 0-50 kOe. In particular, the rotating magnetocaloric effect in ErNi single crystal reaches its maximum under a relatively low field, and the maximum rotating entropy change with a value of 9.3 J (kg K)-1 is obtained by rotating the applied field from the [011] to [100] directions under 13 kOe. These results suggest that ErNi could be a promising candidate for magnetic refrigeration working at liquid-helium temperature region. Moreover, a complicated transport behavior is uncovered in ErNi single crystal, which is attributed to the complex magnetic states and magnetic polaronic effect. Both positive and negative magnetoresistance are observed. A considerable large magnetoresistance with the value of -34.5% is acquired at 8 K under 50 kOe when the field is along the [100] direction.