Electron counts, structural stability, and magnetism in BaCuSn2-CeNi1-Si2-type YT Ge2 (T= Cr, Mn, Fe, Co, and Ni)

Superconductivity in Y4RuGe8 with a Vacancy-Ordered CeNiSi2-Type Superstructure

“…54 The appearance of superconductivity in Y 4 RuGe 8 is unexpected since all other similar compounds YT 1−x Ge 2 (T = transition metals) with disordered transition metal sites exhibit Pauli paramagnetism but no superconductivity (above 2 K). 13,55 Measurements below 2 K may be necessary to check for the possibility of superconductivity in those systems. The superconductivity observed in Y 4 RuGe 8 may also be closely related to the ordering of Ru vacancies which reduces the disorder level significantly compared with other YT 1−x Ge 2 since strong disorder is believed to be detrimental to conventional superconductivity.…”

“…Many rare earth transition metal germanides RT 1– x Ge 2 ( x is the vacancy value, 0 ≤ x < 1) with the CeNiSi 2 -type structure show vacancies on the transition metal site. − Most of those do not appear to exhibit any superstructure induced by vacancy ordering even though x is very close to a rational number such as 0.5 or 0.75, which leads to massive atomic disorder on the transition metal sites. However, a significant amount of vacancy disorder in RT 1– x Ge 2 can be detrimental to certain quantum states, such as superconductivity as exemplified in YFe 2 Ge 2 . , Disorder may prevent materials from showing their intrinsic properties and also make it difficult to interpret the phenomena.…”

Magnetic properties induced by the Yb-valence inhomogeneity in the layered Kondo-lattice compound Yb4RuGe8

“…First, we discuss the Ru contribution to the magnetic properties. The yttrium-based compounds YCr 0.22 Ge 2 , YFe 0.282 Ge 2 , and YCo 0.493 Ge 2 exhibit Pauli-paramagnetic behaviors [60], and Y 4 MnGe 8 shows the enhanced Pauliparamagnetic behavior [54]. In addition, the Yb valence and χ T show similar temperature dependence in Yb 4 CrGe 8 and Yb 4 MnGe 8 [55].…”