193 research outputs found
Two geometrically frustrated magnets studied by neutron diffraction
In the pyrochlore compounds, TbTiO and TbSnO, only
the Tb ions are magnetic. They exhibit quite abnormal -- and, in view of
their chemical similarity, strikingly different -- magnetic behaviour, as
probed by neutron diffraction at ambient and applied pressure.
TbTiO is a cooperative paramagnet (`spin liquid'), without long
range order at ambient pressure; however, it does become ordered under
pressure. By contrast, TbSnO enters an "ordered spin ice" state
already at ambient pressure. We analyse a simple model which already clearly
exhibits some of the qualitative features observed experimentally. Overall,
comparing these two compounds emphasizes the power of small perturbations in
selecting low-temperature states in geometrically frustrated systems.Comment: 6 pages, 4 figures, International Conference on Neutron Scattering
Sydney(2005
Spin-Charge Separation in Two-dimensional Frustrated Quantum Magnets
The dynamics of a mobile hole in two-dimensional frustrated quantum magnets
is investigated by exact diagonalization techniques. Our results provide
evidence for spin-charge separation upon doping the kagome lattice, a prototype
of a spin liquid. In contrast, in the checkerboard lattice, a symmetry broken
Valence Bond Crystal, a small quasi-particle peak is seen for some crystal
momenta, a finding interpreted as a restoration of weak holon-spinon
confinement.Comment: 4 pages, 6 figure
A new neutron study of the short range order inversion in FeCr
We have performed new neutron diffuse scattering measurements in
FeCr solid solutions, in a concentration range 0x0.15, where
the atomic distribution shows an inversion of the short range order. By
optimizing the signal-background ratio, we obtain an accurate determination of
the concentration of inversion x =0.110(5). We determine the near neighbor
atomic short range order parameters and pair potentials, which change sign at
x. The experimental results are compared with previous first principle
calculations and atomistic simulations.Comment: 6 pages; 6 figure
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