NMR evidence for spontaneous electronic chiral order in URhSn

徳永 陽  ; 石飛 尊之; 酒井 宏典   ; 神戸 振作*  ; 播磨 尚朝*; 仲村 愛*; Maurya, A.*; Li, D.*; 本間 佳哉*; 本多 史憲*; 青木 大*; 清水 悠晴*

Tokunaga, Yo; Ishitobi, Takayuki; Sakai, Hironori; Kambe, Shinsaku*; Harima, Hisatomo*; Nakamura, Ai*; Maurya, A.*; Li, D.*; Homma, Yoshiya*; Honda, Fuminori*; Aoki, Dai*; Shimizu, Yusei*

URhSn exhibits successive phase transitions at = 54 K and = 16 K. While the transition at is known to be ferromagnetic, the nature of the intermediate phase between and has remained elusive. Here, we report Sn nuclear magnetic resonance (NMR) measurements on high-quality single crystals of URhSn, which reveal NMR line splittings indicative of symmetry breaking in the intermediate phase. The field-direction and site dependences of these splittings are consistent with antiferroquadrupolar ordering characterized by the space group P321 (No.150). This finding confirms the emergence of a novel form of chiral order driven by electronic degrees of freedom, without an underlying chiral crystal structure in URhSn.