Large Magneto Caloric Effect in (Dy_xGd_(1-x)Ga_5O_(12) for Magnetic Refrigeration below 1K

摘要

A large magneto caloric effect (MCE) has been observed in (Dy_xGd_(1-x))_3Ga_5O_(12) garnet single crystals below 1 K. The experimental results on specific heat show; (1) peak temperature of the specific heat decreases from 0.85 K at x=0 to 0.6 K at x=0.05, (2) temperature dependence of the specific heat at 0 < x < 0.5 is similar to Gd_3Ga_5O_(12), keeping a broad and large peak value, (3) entropy change produced by the external magnetic field of 1 T in a x=0.25 sample is about twice as large as that of x=0 at 0.5 K. The large entropy based on the frustration in the Gd_3Ga_5O_(12) is useful to enhance the MCE using the strong internal field provided by substituting the Dy~(3+) ion for Gd~(3+) ion.