Enhanced magnetocaloric effect in the Tb₂In_1−xAl_x (0 ≤ x ≤ 0.6) alloy by hetero-structural alloying

The evolutions of the crystallographic structure and magnetic phase transition in Tb₂In_1−xAl_x (0 ≤ x ≤ 0.6) alloys are investigated in this work. By gradually alloying antiferromagnetic orthorhombic Tb₂Al, the crystalline structure of ferromagnetic Tb₂In is gradually distorted from the hexagonal type for x ≤ 0.3 to orthorhombic one for x ≥ 0.4. The ferromagnetic ground state for x ≤ 0.4 is also gradually evolved into antiferromagnetic one for x ≥ 0.5. The phase transition temperature is decreased monotonously. At the critical composition of x = 0.4, the weak field-triggered metamagnetism is realized, leading into the enhanced maximum of magnetic entropy change from 6.6 J kg⁻¹ K⁻¹ in Tb₂In to 10.6 J kg⁻¹ K⁻¹ in Tb₂In_0.6Al_0.4 for a field of 5.6 × 10⁶ A/m. The origin is supposed to be from the lattice distortion due to the critical composition at the phase borderline.