Magnetic Field Induced Triple-q Magnetic Order in Trillium Lattice Antiferromagnet EuPtSi Studied by Resonant X-ray Scattering

摘要

Magnetic order in the magnetic-field-induced so-called A phase of cubic chiral antiferromagnet EuPtSi was investigated by resonant X-ray scattering (RXS) near the Eu L-2 absorption edge. The high-intensity RXS signal revealed the triple-q magnetic order of the A phase in a magnetic field applied along the [111] direction. The triple-q order is described by three propagation vectors lying on the plane normal to the magnetic field direction: q(1) = (-delta(3) ,delta(1) ,delta(2)), q(2) = (-delta(2), delta(3), -delta(1)), and q(3)= (delta(1), delta(2), -delta(3)). where delta(1) similar to 0.09, delta(2) similar to 0.20. and delta(3)similar to 0.29. With the high resolution in the reciprocal space achieved in the RXS measurement, it is suggested that the triple-q order strongly couples with the underlying crystal lattice. The triple-q magnetic order is discussed in the context of a magnetic skyrmion lattice where geometrical frustration may play a crucial role.