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Pair correlations, short-range order, and dispersive excitations in the quasi-kagome quantum magnet volborthite

Nilsen, G. J.; Coomer, F. C.; de Vries, M. A.; Stewart, J. R.; Deen, Pascale LU ; Harrison, A. and Ronnow, H. M. (2011) In Physical Review B (Condensed Matter and Materials Physics) 84(17).
Abstract
We present spatial and dynamic information on the s = 1/2 distorted kagome antiferromagnet volborthite, Cu3V2O7(OD)(2) center dot 2D(2)O, obtained by polarized and inelastic neutron scattering. The instantaneous structure factor, S(Q), is dominated by nearest-neighbor pair correlations, with short-range order at wave vectors Q(1) = 0.65(3) angstrom(-1) and Q(2) = 1.15(5) angstrom(-1) emerging below 5 K. The excitation spectrum, S(Q,omega), reveals two steep branches dispersing from Q(1) and Q(2), and a flat mode omega(f) = 5.0(2) meV. The results allow us to identify the crossover at T* similar to 1 K in V-51 NMR and specific-heat measurements as the buildup of correlations at Q(1). We compare our data to theoretical models proposed for... (More)
We present spatial and dynamic information on the s = 1/2 distorted kagome antiferromagnet volborthite, Cu3V2O7(OD)(2) center dot 2D(2)O, obtained by polarized and inelastic neutron scattering. The instantaneous structure factor, S(Q), is dominated by nearest-neighbor pair correlations, with short-range order at wave vectors Q(1) = 0.65(3) angstrom(-1) and Q(2) = 1.15(5) angstrom(-1) emerging below 5 K. The excitation spectrum, S(Q,omega), reveals two steep branches dispersing from Q(1) and Q(2), and a flat mode omega(f) = 5.0(2) meV. The results allow us to identify the crossover at T* similar to 1 K in V-51 NMR and specific-heat measurements as the buildup of correlations at Q(1). We compare our data to theoretical models proposed for volborthite, and also demonstrate that the excitation spectrum can be explained by spin-wave-like excitations with anisotropic exchange parameters, as suggested by recent local-density calculations. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Review B (Condensed Matter and Materials Physics)
volume
84
issue
17
publisher
American Physical Society
external identifiers
  • wos:000296860400001
  • scopus:82455181576
ISSN
1098-0121
DOI
10.1103/PhysRevB.84.172401
language
English
LU publication?
yes
id
e862fad7-4546-46e5-9a74-397ffa6277c8 (old id 2253112)
date added to LUP
2011-12-21 15:37:13
date last changed
2017-07-30 04:09:38
@article{e862fad7-4546-46e5-9a74-397ffa6277c8,
  abstract     = {We present spatial and dynamic information on the s = 1/2 distorted kagome antiferromagnet volborthite, Cu3V2O7(OD)(2) center dot 2D(2)O, obtained by polarized and inelastic neutron scattering. The instantaneous structure factor, S(Q), is dominated by nearest-neighbor pair correlations, with short-range order at wave vectors Q(1) = 0.65(3) angstrom(-1) and Q(2) = 1.15(5) angstrom(-1) emerging below 5 K. The excitation spectrum, S(Q,omega), reveals two steep branches dispersing from Q(1) and Q(2), and a flat mode omega(f) = 5.0(2) meV. The results allow us to identify the crossover at T* similar to 1 K in V-51 NMR and specific-heat measurements as the buildup of correlations at Q(1). We compare our data to theoretical models proposed for volborthite, and also demonstrate that the excitation spectrum can be explained by spin-wave-like excitations with anisotropic exchange parameters, as suggested by recent local-density calculations.},
  articleno    = {172401},
  author       = {Nilsen, G. J. and Coomer, F. C. and de Vries, M. A. and Stewart, J. R. and Deen, Pascale and Harrison, A. and Ronnow, H. M.},
  issn         = {1098-0121},
  language     = {eng},
  number       = {17},
  publisher    = {American Physical Society},
  series       = {Physical Review B (Condensed Matter and Materials Physics)},
  title        = {Pair correlations, short-range order, and dispersive excitations in the quasi-kagome quantum magnet volborthite},
  url          = {http://dx.doi.org/10.1103/PhysRevB.84.172401},
  volume       = {84},
  year         = {2011},
}