Magnetically frustrated ground state of an Yb-based semiconductor YbCuS2 with an effective spin-1/2 zigzag chain

In the present work, we focus on an Yb-based semiconductor YbCuS2, which has been recently proposed as the first substance exhibiting peculiar quantum phases due to the frustrated Yb zigzag chain. We have studied the magnetic and thermal properties of the semiconducting compound YbCuS2 and revealed a phase transition occurs at To = 0.95 K. The magnetic entropy at To is reduced to 20% of Rlog2, which indicates the magnetic fluctuations above To. Moreover, The peculiar phase diagram suggests manifestation of nontrivial quantum phases arising from the geometrical frustration. The aim is to measure the order parameter and possible magnetic structure using the microscopic measurements such as muon spin relaxation and neutron diffraction. The microscopic observation must be an indication of the magnetic frustration arising from the Yb zigzag chain with the effective spin-1/2.