Spin-orbital short-range order on a honeycomb-based lattice. Dan Neumann, National Institute of Standards and Technology, DMR 0944772.
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Spin-orbital short-range order on a honeycomb-based lattice
Dan Neumann, National Institute of Standards and Technology, DMR 0944772
A spin liquid within a solid is a state of matter without static spin order at low temperatures despite strong interactions between local magnetic moments on a lattice. It is thought that competing (frustrated) interactions can result in such behavior, but no definite realization has been documented.
Magnetically frustrated Ba3CuSb2O9 (Fig. 1) has some of the anticipated characteristics. With 0.2 meV resolution the inelastic neutron scattering (Fig. 2) is gapless but shows no temperature-dependent elastic scattering between 25 K and 1.5 K. This indicates spins in Ba3CuSb2O9 do not develop static order but remain in a quantum fluctuating state to the lowest temperatures.
Figure 1. Ba3CuSb2O9 structure showing the 2D honeycomb lattice with the Cu-Sbdumbbells. The disordered structure results from frustrated interactions, during high temperature synthesis, between Cu-Sb dumbbells that carry an electric dipole moment
Ba ions are omitted.
Figure 2. Inelastic neutron scattering from polycrystalline Ba3CuSb2O9, taken with the CHRNS-supported MACS at T=1.5, 25 and 50K.