Abstract
| Original language | English |
|---|---|
| Pages (from-to) | 9275-9287 |
| Number of pages | 13 |
| Journal | Physical Review B: Condensed Matter and Materials Physics |
| Volume | 54 |
| Issue number | 13 |
| DOIs | |
| Publication status | Published - 1996 |
| MoE publication type | A1 Journal article-refereed |
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Magnetic resonance of type-I fcc antiferromagnets. / Heinilä, Marko; Oja, Aarne.
In: Physical Review B: Condensed Matter and Materials Physics, Vol. 54, No. 13, 1996, p. 9275-9287.Research output: Contribution to journal › Article › Scientific › peer-review
TY - JOUR
T1 - Magnetic resonance of type-I fcc antiferromagnets
AU - Heinilä, Marko
AU - Oja, Aarne
PY - 1996
Y1 - 1996
N2 - We calculate magnetic-resonance absorption curves for an assembly of classical spins located in an fcc lattice with spin-spin interactions which stabilize antiferromagnetic order of the first kind. The only source of anisotropy in the model is the dipole-dipole interaction which, at equilibrium, confines the ordered moments into planes perpendicular to the respective type-I ordering vectors. Our principal tool of analysis combines numerical integration of the equations of motion with Monte Carlo simulations. Complete absorption line shapes for classical spins can be calculated using this technique. Spin dynamics is investigated as well by extending our earlier mean-field analysis, the results of which are compared with the simulations. Special attention is paid to a sum rule that relates the intensities of the resonance peaks to the static susceptibility. To this end, we calculate the static susceptibility matrixes for certain single-k and triple-k type-I structures. We investigate, in particular, examples of cases where thermal fluctuations beyond the mean-field theory shift resonance lines from zero frequency to a finite value. It is demonstrated that this effect is related to the so-called ‘‘ordering-by-disorder’’ mechanism in which fluctuations stabilize a unique ground state in a continuously degenerate manifold. Our results explain several features observed in recent NMR studies of antiferromagnetic nuclear-spin ordering in copper and silver at nanokelvin temperatures. Analogies with spin dynamics in solid 3He and superfluid 3A are briefly discussed.
AB - We calculate magnetic-resonance absorption curves for an assembly of classical spins located in an fcc lattice with spin-spin interactions which stabilize antiferromagnetic order of the first kind. The only source of anisotropy in the model is the dipole-dipole interaction which, at equilibrium, confines the ordered moments into planes perpendicular to the respective type-I ordering vectors. Our principal tool of analysis combines numerical integration of the equations of motion with Monte Carlo simulations. Complete absorption line shapes for classical spins can be calculated using this technique. Spin dynamics is investigated as well by extending our earlier mean-field analysis, the results of which are compared with the simulations. Special attention is paid to a sum rule that relates the intensities of the resonance peaks to the static susceptibility. To this end, we calculate the static susceptibility matrixes for certain single-k and triple-k type-I structures. We investigate, in particular, examples of cases where thermal fluctuations beyond the mean-field theory shift resonance lines from zero frequency to a finite value. It is demonstrated that this effect is related to the so-called ‘‘ordering-by-disorder’’ mechanism in which fluctuations stabilize a unique ground state in a continuously degenerate manifold. Our results explain several features observed in recent NMR studies of antiferromagnetic nuclear-spin ordering in copper and silver at nanokelvin temperatures. Analogies with spin dynamics in solid 3He and superfluid 3A are briefly discussed.
U2 - 10.1103/PhysRevB.54.9275
DO - 10.1103/PhysRevB.54.9275
M3 - Article
VL - 54
SP - 9275
EP - 9287
JO - Physical Review B
JF - Physical Review B
SN - 2469-9950
IS - 13
ER -