The structural and magnetic properties of the compound Tm5Ge4

Abstract

The compound Tm₅Ge₄ is the last one in the family of R₅Ge₄ (R = rare earth elements with magnetic moments) compounds (exclusive of Pm and Eu) whose magnetic properties are still unknown. We prepared high quality Tm₅Ge₄, and report the detailed crystal structure and magnetic properties. Tm₅Ge₄ crystallizes in the Sm₅Ge₄-type orthorhombic structure at room temperature, and orders antiferromagnetically at = 13 and T_N = 21 K. The paramagnetic Curie temperature of Tm₅Ge₄ is positive (θ_p = 16 K), and the effective magnetic moment (p_eff = 7.4 μ_B/Tm) is in good agreement with the theoretical value of 7.56 μ_B/Tm³⁺. The ac susceptibility of Tm₅Ge₄ shows obvious frequency dependence behaviors suggesting the existence of a ferromagnetic cluster in the antiferromagnetic substance. According to the magnetic hysteresis loop, the intrinsic coercivity of Tm₅Ge₄ is 2616 Oe at 2 K. Tm₅Ge₄ exhibits an oscillating magnetocaloric effect owing to a metamagnetic-like transformation induced by a critical magnetic field below 21 K.