Critical slowing-down and field-dependent paramagnetic fluctuations in the skyrmion host EuPtSi; SR and NMR studies

Higa, Nonoka*; Ito, Takashi   ; Yogi, Mamoru*; Hattori, Taisuke; Sakai, Hironori   ; Kambe, Shinsaku  ; Guguchia, Z.*; Higemoto, Wataru  ; Nakashima, Miho*; Homma, Yoshiya*; Nakamura, Ai*; Honda, Fuminori*; Shimizu, Yusei*; Aoki, Dai*; Kakihana, Masashi*; Hedo, Masato*; Nakama, Takao*; Onuki, Yoshichika*; Tokunaga, Yo  

We report the results of SR and Si NMR measurements carried out on the cubic chiral magnet EuPtSi. Our zero-field SR experiments revealed the development of critical slowing down of Eu spin fluctuations over a relatively wide critical region above . We also found from Si NMR that the spin fluctuations are strongly suppressed by magnetic field in the paramagnetic state above 20K. These characteristic spin dynamics observed over a wide region of temperature and magnetic field suggest the presence of magnetic frustration in the spin system. Such frustration would underlie the mechanism stabilizing the short-period skyrmion lattice observed in this compound.