Magnetic fluctuation and first-order transition in trillium lattice of EuPtSi observed by Eu Mssbauer spectroscopy

Homma, Yoshiya*; Kakihana, Masashi*; Tokunaga, Yo  ; Yogi, Mamoru*; Nakashima, Miho*; Nakamura, Ai*; Shimizu, Yusei*; Li, D.*; Maurya, A.*; Sato, Yoshiki*; Honda, Fuminori*; Aoki, Dai*; Amako, Yasushi*; Hedo, Masato*; Nakama, Takao*; Onuki, Yoshichika*

We report the results of Eu Mssbauer spectroscopy on EuPtSi with a chiral structure belonging to the P23 space group at zero magnetic field. The paramagnetic single absorption forms a magnetic splitting profile directly below 4.0 K and the spectrum at 3.9 K consists of the sum of the paramagnetic single absorption and the magnetic splitting absorption, which indicates a first-order transition at 4.0 K. The temperature dependence of the effective hyperfine fields at the Eu nucleus follows a power law indicates a full moment of Eu ions.