Structural distortions in the spin-gap regime of the quantum antiferromagnet SrCu{sub 2}(BO{sub 3}){sub 2}

Journal Article · Tue Dec 15 04:00:00 EST 2009 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2009.09.017· OSTI ID:21372421

Vecchini, C ^[1]; Adamopoulos, O ^[1]; Chapon, L C ^[2]; Lappas, A ^[1]; Kageyama, H ^[3]; Ueda, Y ^[4]; Zorko, A ^[5]

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1. Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, Vassilika Vouton, 711 10 Heraklion, Crete (Greece)
2. ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire, OX11 0QX (United Kingdom)
3. Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan)
4. Institute of Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan)
5. Institute Jozef Stefan, Jamova 39, 1000 Ljubljana (Slovenia)

We report the first crystallographic study within the low-temperature (<40 K) spin-gap region of the two-dimensional frustrated antiferromagnet SrCu{sub 2}(BO{sub 3}){sub 2}. The crystal system does not deviate from the tetragonal I-42m space group symmetry. However, our high-resolution neutron powder diffraction measurements uncover subtle structural modifications below 34 K, concomitant to the formation of the dimer singlet ground state. Intimate spin-lattice coupling leads to negative thermal expansion of the tetragonal structure, which reflects into particular local lattice adjustments. The extracted structural parameters suggest the reduction of the buckling found in the copper-borate planes and the strengthening of the leading, in-plane intra-dimer superexchange interaction. The observed contraction along the c-axis, associated with the inter-dimer exchange in adjacent layers, indicates the involvement of weaker three-dimensional interactions in the magnetic properties. The rules posed by the crystal symmetry do not preclude Dzyaloshinsky-Moriya interactions, which therefore remain as an important source of spin anisotropy necessary to rationalise the ground state behaviour. - Abstract: We report the first crystallographic study within the low-temperature spin-gap region of the two-dimensional frustrated antiferromagnet SrCu{sub 2}(BO{sub 3}){sub 2}. Subtle spin-lattice coupling was unveiled in the low-temperature region. Display Omitted

• OSTI ID: 21372421
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 12 Vol. 182; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALKALINE EARTH METAL COMPOUNDS
ANGULAR MOMENTUM
BORATES
BORON COMPOUNDS
COHERENT SCATTERING
COPPER COMPOUNDS
CRYSTALLOGRAPHY
DIFFRACTION
DIMERS
EXPANSION
MAGNETIC PROPERTIES
NEUTRON DIFFRACTION
OXYGEN COMPOUNDS
PARTICLE PROPERTIES
PHYSICAL PROPERTIES
SCATTERING
SPACE GROUPS
SPIN
STRONTIUM COMPOUNDS
SYMMETRY GROUPS
TEMPERATURE RANGE
TEMPERATURE RANGE 0013-0065 K
THERMAL EXPANSION
TRANSITION ELEMENT COMPOUNDS