Magnetic-field induced quantum phases in a magnetically frustrated Yb-zigzag chain system YbCuS2

In a Yb-based semiconductor YbCuS2, where trivalent Yb ions form a low-dimensional zigzag chain, the competitive AFM interactions enhance magnetic fluctuations due to the magnetic frustration. A phase transition occurs at TO = 0.95 K, where the magnetic entropy is reduced to 20% of Rln2. TO is robust for B < 4 T, and TO increases to higher temperatures but decreases for B > 7 T. The peculiar phase diagram suggests manifestation of magnetic-field induced quantum phases. Magnetic reflections were observed below TO by powder neutron diffraction experiments at WISH. The magnetic structure is characterized by an incommensurate propagation vector and the ordered moment is reduced. The aim of the present experiment is to investigate evolution of the order parameters and possible magnetic structures in the magnetic-field induced phases by the neutron diffraction measurements on WISH.