Magnetic field induced triple- magnetic order in trillium lattice antiferromagnet EuPtSi studied by resonant X-ray scattering

Tabata, Chihiro*; Matsumura, Takeshi*; Nakao, Hironori*; Michimura, Shinji*; Kakihana, Masashi*; Inami, Toshiya*; Kaneko, Koji   ; Hedo, Masato*; Nakama, Takao*; Onuki, Yoshichika*

The magnetic order in the magnetic-fild-induced so-called A phase of cubic chiral antiferromagnet EuPtSi was investigated by resonant X-ray scattering (RXS) near the Eu edge. The high flux RXS signal under the magnetic field applied along [111] revealed the first and second order satellite magnetic reflections, indicating that the A phase is a triple- magnetic ordered state that is described by three propagation vectors lying in the plane normal to the magnetic field direction; , , and . With the high resolution in the reciprocal space achieved in the RXS measurement, it is suggested that the triple- order strongly couples with the underlying crystal lattice. The triple- magnetic order is discussed in the context of a magnetic skyrmion lattice on which the geometrical frustration may play a crucial role.