Enhanced magnetocaloric effects in Gd₂In_1−xAl_x (0.4 ≤ x ≤ 1) system by the hysteresis-free metamagnetism

By gradually substituting Al for In in Gd₂In_1−xAl_x (0.4 ≤ x ≤ 1) system, the hexagonal structure for Gd₂In_1−xAl_x (x ≤ 0.6) is gradually evolved into orthorhombic one for x ≥ 0.7. The phase transition temperature is monotonously decreased. At the critical composition of x = 0.7, the second-order phase transformation in hexagonal Gd₂In_1−xAl_x (x ≤ 0.6) is evolved into the first-order-like metamagnetic one without conventional hysteresis in orthorhombic Gd₂In_1−xAl_x (x ≥ 0.7), leading into the enhanced magnetic entropy change and adiabatic temperature change. A lambda-like anomaly on the C_p-T curves is also caused. Due to being close to the phase borderline separating hexagonal and orthorhombic structure, such enhanced magnetocaloric effect is considered to be from the greatly distorted lattice.