低温工学
Online ISSN : 1880-0408
Print ISSN : 0389-2441
ISSN-L : 0389-2441
解説
キラルな結晶構造を有するC40系物質TaAlxGe2-xでの超伝導発現
小泉 太護木佐貫 晋吾門田 健太髙阪 勇輔 宍戸 寛明戸川 欣彦
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2025 年 60 巻 4 号 p. 156-163

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We review superconductors with a chiral crystal structure (chiral superconductors), which lack horizontal and vertical mirrors and an inversion center. Very few chiral superconductors have been reported so far; this is primarily because material design of chiral inorganic crystals still remains challenging. Therefore, we show that an element substitution of the existing chiral inorganic materials could be a useful method for the material discovery of chiral superconductors. We present a new family of chiral intermetallic superconductors TaAlxGe2-x. Magnetic susceptibility, magnetization curves, and electrical resistivity revealed type-II superconductivity, with a superconducting transition temperature Tc from 2.0 to 2.2 K in TaAlxGe2-xx = 0.2-0.4). An emergence of superconductivity is discussed in relation to changes in the lattice constants associated with the Al substitution. These results suggest that the C40-type chiral disilicides and digermanides TX2T = Nb, Ta and X = Si, Ge) are a promising family of materials for exploring chiral superconductors. Chiral superconductors could potentially have unique attractive properties, which have not been studied well in noncentrosymmetric superconductors, as chiral superconductors exhibit nontrivial physical phenomena, such as nonreciprocal electrical magnetochiral anisotropy and chirality-induced spin selectivity, in addition to the formation of unconventional Cooper pair states and enhancing the properties of superconductivity.

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© 公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)
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