Hague, J. P.; Chung, E. M. L.; Visser, D.; Balakrishnan, G.; Clementyev, E.; Paul, D. McK. and Lees, M. R.
|DOI (Digital Object Identifier) Link:||http://dx.doi.org/10.1088/0953-8984/17/46/007|
|Google Scholar:||Look up in Google Scholar|
We describe neutron inelastic scattering measurements of spin waves in the quasi-two-dimensional antiferromagnet FeTa2O6. The intrinsic spin wave dispersion for a single domain is deduced from linear spin wave theory and used to determine the intra-plane exchange coefficients. Almost dispersion-free excitations are observed along the c* direction perpendicular to the magnetic planes. This justifies the neglect of inter-plane coupling, which merely stabilizes the ordered configuration below TN. Spin wave theory yields values for the nearest neighbour and next nearest neighbour exchange constants on perpendicular diagonals of J = −0.040(9) meV, J'/J = 0.20(0), J''/J = 0.23(9), and the anisotropy parameter D = 0.31(8) meV. The large value of D shows an Ising-like spin configuration to be consistent with the experimental data. Measurements of the temperature dependence of the scattering show that magnetic excitations persist to at least 20 K (over two times TN) due to the extensive 2D short range order. This is a highly unusual result, and has consequences for the understanding of two-dimensional spin systems.
|Item Type:||Journal Article|
|Academic Unit/Department:||Science > Physical Sciences|
|Interdisciplinary Research Centre:||Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)
Biomedical Research Network (BRN)
|Depositing User:||James Hague|
|Date Deposited:||30 Jun 2009 08:46|
|Last Modified:||07 Mar 2014 13:49|
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