Pikul A P, Samsel-Czekała M, Chajewski G, Romanova T, Hackemer A, Gorzelniak R, Wiśniewski P, Kaczorowski D
Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P Nr 1410, 50-950 Wrocław 2, Poland.
J Phys Condens Matter. 2017 May 17;29(19):195602. doi: 10.1088/1361-648X/aa6832. Epub 2017 Mar 21.
Motivated by the recent discovery of exotic superconductivity in YFeGe we undertook reinvestigation of formation and physical properties of yttrium-based 1:2:2 silicides. Here we report on syntheses and crystal structures of the YTE Si compounds with TE = Cr, Co, Ni, Rh, Pd and Pt, and their low-temperature physical properties measurements, supplemented by results of fully relativistic full-potential local-orbital minimum basis band structure calculations. We confirm that most of the members of that family crystallize in a tetragonal ThCrSi-type structure (space group I4/mmm) and have three-dimensional Fermi surface, while only one of them (YPtSi) forms with a closely-related primitive CaBeGe-type unit cell (space group P4/nmm) and possess quasi-two-dimensional Fermi surface sheets. Physical measurements indicated that BCS-like superconductivity is observed only in YPtSi (T = 1.54 K) and YPdSi (T = 0.43 K), while no superconducting phase transition was found in other systems at least down to 0.35 K. Thermal analysis showed no polymorphism in both superconducting phases. No clear relation between the superconductivity and the crystal structure (and dimensionality of the Fermi surface) was observed.
受近期在YFeGe中发现奇异超导性的启发，我们对钇基1:2:2硅化物的形成和物理性质进行了重新研究。在此，我们报告了TE = Cr、Co、Ni、Rh、Pd和Pt的YTE Si化合物的合成和晶体结构，以及它们的低温物理性质测量结果，并辅以全相对论全势局域轨道最小基能带结构计算结果。我们证实，该家族的大多数成员结晶为四方ThCrSi型结构（空间群I4/mmm），具有三维费米面，而其中只有一种（YPtSi）形成与密切相关的原始CaBeGe型晶胞（空间群P4/nmm），并拥有准二维费米面片。物理测量表明，仅在YPtSi（T = 1.54 K）和YPdSi（T = 0.43 K）中观察到类BCS超导性，而在其他系统中至少在0.35 K以下未发现超导相变。热分析表明，两个超导相均无多晶型现象。未观察到超导性与晶体结构（以及费米面的维度）之间的明确关系。
