Volume 32, Issue 3, March 2006
Index of content:
- LOW-TEMPERATURE MAGNETISM
32(2006); http://dx.doi.org/10.1063/1.2178471View Description Hide Description
The phase states of a non-Heisenberg ferromagnet with anisotropy of both the Heisenberg and biquadratic interactions are investigated. Limiting cases of the model are the model with a biquadratic interaction and the three-component non-Heisenberg ferromagnet. The phase transitions both in respect to the material constants and in temperature are investigated for the 2D and 3D magnets. The phase diagrams of the system are constructed for various relations of the system parameters. It is shown that in the given model the soft mode is a branch of quasimagnetic and not quasielastic excitations.
32(2006); http://dx.doi.org/10.1063/1.2178472View Description Hide Description
A study is made of the generation of electromagnetic oscillations by a sound wave in a weak ferromagnet with a higher-order symmetry axis. The electric fields are calculated for different states with different orientations of the antiferromagnetic vector. It is shown that the magnetoelasticinteraction leads to an additional phase difference between the electromagnetic and sound waves.
32(2006); http://dx.doi.org/10.1063/1.2178475View Description Hide Description
Magnetic resonance studies of the metalorganic antiferromagnet are carried out over a wide range of frequencies (25–) and temperatures (1.8–). The data on the temperature dependence of the magnetic susceptibility attest to a low-dimensional magnetic structure of this crystal. The results of resonance studies at a temperature of are used to construct the frequency–field diagram of the antiferromagnetic resonancespectrum of this compound; it is described by the model of a biaxial rhombic antiferromagnet with the following parameters: , , , , , . Two-magnon and nonresonance three-magnon absorption is observed, and the weakest interchain exchange interaction is estimated as .
32(2006); http://dx.doi.org/10.1063/1.2178476View Description Hide Description
An attempt is made at a theoretical interpretation of the observed collapse of the magnetic state in solid oxygen under pressure. The basic premise rests on a growing role of the biquadratic intermolecular exchange with increasing pressure, leading to instability of the initial antiferromagnetic state.
32(2006); http://dx.doi.org/10.1063/1.2178479View Description Hide Description
The critical properties of the 3D frustrated Heisenberg model on a layered triangular lattice are investigated by the Monte Carlo method. The theory of finite-size scaling is used to calculate the magnetic and chiral critical exponents of the specific heat , susceptibility , magnetization , and correlation length . It is shown that the 3D frustrated Heisenberg model on a layered triangular lattice forms a new universality class of critical behavior.