Emergence of long-range order in sheets of magnetic dimers Academic Article uri icon

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abstract

  • Quantum spins placed on the corners of a square lattice can dimerize and form singlets, which then can be transformed into a magnetic state as the interactions between dimers increase beyond threshold. This is a strictly 2D transition in theory, but real-world materials often need the third dimension to stabilize long-range order. We use high pressures to convert sheets of Cu(2+) spin 1/2 dimers from local singlets to global antiferromagnet in the model system SrCu2(BO3)2. Single-crystal neutron diffraction measurements at pressures above 5 GPa provide a direct signature of the antiferromagnetic ordered state, whereas high-resolution neutron powder and X-ray diffraction at commensurate pressures reveal a tilting of the Cu spins out of the plane with a critical exponent characteristic of 3D transitions. The addition of anisotropic, interplane, spin-orbit terms in the venerable Shastry-Sutherland Hamiltonian accounts for the influence of the third dimension.

authors

  • Haravifard, S
  • Banerjee, A
  • van Wezel, J
  • Silevitch, DM
  • dos Santos, AM
  • Lang, JC
  • Kermarrec, E
  • Srajer, G
  • Gaulin, Bruce D
  • Molaison, JJ
  • Dabkowska, HA
  • Rosenbaum, TF

publication date

  • October 7, 2014