Volume 32, Issue 1, January 2006
Index of content:
- LOW-TEMPERATURE MAGNETISM
32(2006); http://dx.doi.org/10.1063/1.2161929View Description Hide Description
The anomalies arising in the reflection of a bulk TM wave from the surface of a slab of a nongyrotropic multiferroic on account of anisotropy of the magnetoelectric interaction are investigated for the example of a ferroelectric antiferromagnet in the collinear phase under the condition that the ferroelectric axis is perpendicular to the interface between the media.
32(2006); http://dx.doi.org/10.1063/1.2161931View Description Hide Description
X-ray studies of the magnet have shown that this compound belongs to the monoclinic class with a chain structure. The susceptibility and magnetization of single crystals are investigated experimentally in the temperature region 0.4–100 K and at magnetic fields up to 2 T. The angular dependence of the susceptibility shows that at low temperatures a purely Ising anisotropy is realized in this compound: there exists but one component of the moment, along the axis. The temperature dependence of the susceptibility has a maximum at , and the curve obtained at 0.5 K exhibits substantial nonlinearity at low fields, as is characteristic of an ordered state. Analysis of the experimental data in the mean field approximation suggests that this state is a singlet Ising antiferromagnet with , a value determined from the susceptibility data. At extremely low temperatures a collinear antiferromagnetic structure with equivalent sublattices is realized in the sample, according to estimates made. The high-temperature behavior of the susceptibility is evidence of the presence of an excited quasi-doublet in the vicinity of 35 K.
32(2006); http://dx.doi.org/10.1063/1.2161932View Description Hide Description
An effect wherein the magnetic resonance position is stabilized by a magnetic-field modulation periodic in time is investigated in a two-level system in the density-matrix formalism. An exact solution for the density matrix at resonance is found. It is shown that at resonance the spin-flip transition probability is independent of the shape of the field, i.e., the fundamental resonance is stabilized against a matched variation of the longitudinal and transverse magnetic fields. A differential equation for the transition probability is obtained. The dependence of the time-averaged spin-flip probability an normalized Larmor frequency is investigated numerically for different model parameters with allowance for dissipation and decoherence. It is shown that the resonancelinewidths increase substantially with increasing dissipation and decoherence. The position of the fundamental resonance is independent of the field deformation and the dissipation; only the width of the resonance varies. The odd parametric (multiphoton)resonance transitions are investigated. The static magnetization induced by a harmonized field is examined. This study may find application for analysis of interference experiments, refinement of the design of magnetic spectrometers, and manipulation of qubits.