Possible multigap superconductivity and magnetism in single crystals of superconducting La2Pt3Ge5 and Pr2Pt3Ge5.

We herein describe our investigation of the superconducting and magnetic properties of the rare-earth ternary germanide intermetallic compounds La2Pt3Ge5 and Pr2Pt3Ge5. Single crystals of La2Pt3Ge5 and Pr2Pt3Ge5 were synthesized using the high-temperature metal flux method. Both types of crystal formed in a U2Co3Si5-type orthorhombic structure (space group I bam). La2Pt3Ge5 showed the onset of superconducting phase transition at Tc = 8.1 K, which, to the best of our knowledge, is the highest Tc of all the R2M3X5 (R = rare-earth elements, M = transition metal, and X = s-p metal) superconductors, and from the specific heat data, it was found to have multigap superconductivity. Pr2Pt3Ge5 showed both a superconducting phase transition at Tc = 7.8 K and two antiferromagnetic transitions at TN1 = 3.5 K and TN2 = 4.2 K, which indicates the coexistence of superconductivity and magnetism. However, the correlation between the superconductivity and the magnetism was too weak to be observed. In its normal state, Pr2Pt3Ge5 revealed strong magnetic anisotropy, probably due to the crystalline electric field effect. [ABSTRACT FROM AUTHOR]