新奇超伝導体UTe単結晶育成法の改善

Improvement of a method for growing single crystals of novel superconductor UTe

酒井 宏典   ; Opletal, P.  ; 常盤 欣文  ; 山本 悦嗣  ; 徳永 陽  ; 神戸 振作  ; 芳賀 芳範   

Sakai, Hironori; Opletal, P.; Tokiwa, Yoshifumi; Yamamoto, Etsuji; Tokunaga, Yo; Kambe, Shinsaku; Haga, Yoshinori

スピン三重項超伝導体として注目されるUTeは試料合成法の最適化が進み、超伝導発見当初の超伝導転移温度=1.6Kが2Kと上昇し、比熱における以下の残留状態密度は当初の50%から20%まで下がってきた。最近、我々は従来の化学輸送法ではなく、新しいフラックス法によって、=2.1KのUTe単結晶育成に成功し、比熱における残留状態密度がさらに低く、電気抵抗の残留抵抗率の飛躍的な向上を示すことがわかった。当日は、このフラックス法の最適化の過程について報告したい。

The superconducting transition temperature in the spin-triplet superconductor UTe increases from the initial reported value of 1.6 K to 2.0 K as the newly reported one improving the growth condition. We have developed a growth method for the superconductor UTe that is different from the usual chemical vapor phase transport method. As a result, we have succeeded in growing high-purity UTe crystals at =2.1 K and confirmed that the residual specific heat below is very low and the residual ratio of electrical resistance is very large. We report the optimization of the newly developed method for UTe.