TEION KOGAKU (Journal of Cryogenics and Superconductivity Society of Japan)
Online ISSN : 1880-0408
Print ISSN : 0389-2441
ISSN-L : 0389-2441
Review Article
Superconductivity in Al-substituted Tantalum Germanites TaAlxGe2-x with a C40 Chiral Crystal Structure
Daigo KOIZUMIShingo KISANUKIKenta MONDENYusuke KOUSAKA Hiroaki SHISHIDOYoshihiko TOGAWA
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2025 Volume 60 Issue 4 Pages 156-163

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Abstract

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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© by Cryogenics and Superconductivity Society of Japan (Cryogenic Association of Japan)
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