Spin dynamics, short-range order, and spin freezing in Y{sub 0.5}Ca{sub 0.5}BaCo{sub 4}O{sub 7}

Journal Article · Sat Jan 15 00:00:00 EST 2011 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PHYSREVB.83.024405· OSTI ID:21538061

Stewart, J R ^[1]; Ehlers, G ^[2]; Mutka, H; Fouquet, P ^[3]; Payen, C ^[4]; Lortz, R ^[5]

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1. ISIS Facility, Rutherford Appleton Laboratory, Didcot, Oxford OX11 0QX (United Kingdom)
2. Neutron Scattering Science Division, Oak Ridge National Laboratory, Building 8600, Oak Ridge, Tennessee 37831-6475 (United States)
3. Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, F-38042 Grenoble Cedex 9 (France)
4. Institut des Materiaux Jean Rouxel (IMN), Universite de Nantes-CNRS, BP 32229, F-44322 Nantes Cedex 3 (France)
5. Department of Condensed Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, CH-1211 Geneva 4 (Switzerland)

Y{sub 0.5}Ca{sub 0.5}BaCo{sub 4}O{sub 7} was recently introduced as a possible candidate for capturing some of the predicted classical spin kagome ground-state features. Stimulated by this conjecture, we have taken up a more complete study of the spin correlations in this compound with neutron scattering methods on a powder sample characterized with high-resolution neutron diffraction and the temperature dependence of magnetic susceptibility and specific heat. We have found that the frustrated near-neighbor magnetic correlations involve not only the kagome planes but concern the full Co sublattice, as evidenced by the analysis of the wave-vector dependence of the short-range order. We conclude from our results that the magnetic moments are located on the Co sublattice as a whole and that correlations extend beyond the two-dimensional kagome planes. We identify intriguing dynamical properties, observing high-frequency fluctuations with a Lorentzian linewidth {Gamma}{<=}20 meV at ambient temperature. On cooling a low-frequency ({approx}1 meV) dynamical component develops alongside the high-frequency fluctuations, which eventually becomes static at temperatures below T{approx_equal}50 K. The high-frequency response with an overall linewidth of {approx}10 meV prevails at T{<=}2 K, coincident with a fully elastic short-range-ordered contribution.

• OSTI ID: 21538061
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Vol. 83, Issue 2; Other Information: DOI: 10.1103/PhysRevB.83.024405; (c) 2011 American Institute of Physics; ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
36 MATERIALS SCIENCE
BARIUM COMPOUNDS
CALCIUM COMPOUNDS
COBALT COMPOUNDS
CORRELATIONS
FLUCTUATIONS
FREEZING
GROUND STATES
MAGNETIC MOMENTS
MAGNETIC SUSCEPTIBILITY
NEUTRON DIFFRACTION
OXYGEN COMPOUNDS
SPECIFIC HEAT
SPIN
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0000-0013 K
TEMPERATURE RANGE 0013-0065 K
TWO-DIMENSIONAL CALCULATIONS
YTTRIUM COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
ANGULAR MOMENTUM
COHERENT SCATTERING
DIFFRACTION
ENERGY LEVELS
MAGNETIC PROPERTIES
PARTICLE PROPERTIES
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
SCATTERING
TEMPERATURE RANGE
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
VARIATIONS