Novel magnetism in the Cu-based square lattice compound (CsCl)2Cu(VO3)2

We have been investigating the (nearly) square lattice compound (CsCl)2Cu(VO3)2 for possible novel magnetism due to its two-dimensional nature. Our studies (x-ray diffraction, bulk susceptibility, specific heat, ESR, and 133Cs NMR) have revealed a structural transition at about 140 K and magnetic ordering transitions at 2.7 K and 1.5 K. NMR and ESR measurements suggest an onset around 8 K. The 2.7 K transition appears to be to a ferromagnetic state though there are various unusual features. Also, Xpress muSR measurements were recently conducted, which confirmed the feasibility of a detailed study at the ISIS facility. We are proposing zero-field muSR measurements to infer the temperature variation of the magnetic order parameter and shed more light on the effect of a magnetic field on the ordering. Through a separate proposal, we are also planning neutron diffraction measurements on this sample to better understand the nature of the ordered state.