Spiral phase and spin waves in the quasi-two-dimensional antiferromagnet Ba{sub 2}CuGe{sub 2}O{sub 7}

Journal Article · Sun Dec 01 04:00:00 EST 1996 · Physical Review, B: Condensed Matter

DOI:https://doi.org/10.1103/PhysRevB.54.15163· OSTI ID:397607

Zheludev, A; Shirane, G ^[1]; Sasago, Y; Kiode, N; Uchinokura, K ^[2]

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1. Brookhaven National Laboratory, Upton, New York 11973-5000 (United States)
2. Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113 (Japan)

The quasi-two-dimensional square-lattice antiferromagnet Ba{sub 2}CuGe{sub 2}O{sub 7} was studied by neutron scattering and bulk magnetic techniques. An incommensurate magnetic spiral structure with the propagation vector (1+{zeta},1+{zeta},0) ({zeta}=0.027) was observed below {ital T}{sub {ital N}}=3.26 K. Magnetic ordering occurs with a two-dimensional-like critical exponent {beta}{approx_equal}0.15. The spin dynamics can be adequately described by conventional spin-wave theory with two exchange constants: nearest-neighbor in-plane antiferromagnetic coupling {ital J}{sub 1}{approx_equal}0.48 meV and interplane ferromagnetic interaction {ital J}{sub {perpendicular}}{approx_equal}0.013 meV. This set of exchange parameters apparently fails to explain the spiral order. The noncentrosymmetric crystal structure suggests that the incommensurate phase may be the result of a Dzyaloshinskii-Moriya instability of the N{acute e}el ground state. {copyright} {ital 1996 The American Physical Society.}

• Research Organization: Brookhaven National Laboratory
• DOE Contract Number: AC02-76CH00016
• OSTI ID: 397607
• Journal Information: Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 21 Vol. 54; ISSN PRBMDO; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANTIFERROMAGNETIC MATERIALS
BARIUM OXIDES
COPPER OXIDES
EXCHANGE INTERACTIONS
GERMANIUM OXIDES
INCOMMENSURATE PHASES
INELASTIC SCATTERING
MAGNETIC PROPERTIES
MAGNETIC STRUCTURE
NEUTRON BEAMS
PHASE TRANSFORMATIONS
SPIN WAVES
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0000-0013 K
TEMPERATURE RANGE 0013-0065 K
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K