Date(s) - Mar 20 2017
1:15 PM - 2:15 PM
Room 335, McCullough Building
Trapped magnetic defects at the origin of the spin liquid state in the frustrated magnet SrDy2O4
Paul Scherrer Institut (PSI), Villigen, Switzerland
Frustrated magnetism can lead to novel strongly correlated states such as spin liquids. Another route to strong entanglement in magnetic systems is low-dimensionality since it suppresses the tendency to order in a long range conventional state. The occurrence of competing interactions in low-dimensional magnetic materials combines these two approaches, increasing the opportunity to uncover novel spin liquid states. The compounds SrR2O4 (R = rare earth) are therefore good candidates to investigate strongly correlated magnetism due to the presence of zig-zag chains, which are quasi-one-dimensional (1D) and magnetically frustrated . They show a variety of unconventional behaviours: low-dimensional correlations, coexistence of different magnetic orders, magnetization plateaus and field-induced ordered states. The frustrated magnet SrDy2O4 is particularly interesting owing to the absence of long range order down to T = 60 mK in zero field .
We investigated in details the magnetic correlations in SrDy2O4 using powder and single crystal neutron diffraction as well as magnetic susceptibility. Diffuse neutron scattering indicates short range correlations that are consistent with those of the 1D Ising zig-zag chain model. AC susceptibility measurements indicate a slowing down of the fluctuations at low temperatures. We attribute this behaviour to the domain walls in the zig-zag chains. Experimental evidence of a dimensionality crossover at low temperatures in SrDy2O4 suggest that the domains walls are trapped because of interchain interactions, precluding long range order to the lowest temperatures in zero field . An applied magnetic field modifies the magnetic correlations in a complex way that depends on the temperature and field history. The possibility to stabilize a short or a long range field-induced order depends on the initial conditions and confirms the importance of trapped defects in this system.
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