Xuan-Zhang Wang

Magnetic properties of a transverse Ising film with s=1/2

A transverse Ising film, for s=1/2, with a body-centred cubic structure and two (001) surfaces is studied by means of the effective-field theory with correlations. The layer magnetizations and average magnetization of the film as functions of temperature and transverse field are calculated numerically and some interesting results are obtained.

Magnetostatic modes of lateral-magnetic-superlattice films in a transverse field

We discuss some properties of magnetostatic modes of a lateral superlattice (LSL) consisting of a ferromagnetic film patterned into a series of parallel stripes. In contrast to earlier work we assume that the applied magnetic field and static magnetization are transverse to the stripes. The details of the results depend on , the fraction of the patterned film occupied by magnetic material. We find a surface mode for all values of , propagating in a wedge centred about the Voigt direction. In a thick (semi-infinite) LSL the surface mode lies above the bulk continuum and for an LSL of finite thickness the bulk continuum is replaced by a spectrum of discrete guided modes.

The Faraday effect of an antiferromagnetic photonic crystal with a defect layer

A theoretical calculation of the Faraday optical rotation effect of an antiferromagnetic (AF) photonic crystal is presented. This crystal is composed of AF and dielectric (D) layers and contains an AF defect layer. From the theoretical results for the FeF2?SiO2 crystal, we see a defect mode with high transmission and a high Faraday rotation angle in the optical stop band for ?/2?c<105?cm?1. The Faraday rotation of the mode is about 28??mm?1 and 15?times that of the single AF film. Another more striking property is that the rotation in the vicinity of the zero-field AF resonance frequency is even larger than that of the defect mode: about 250?times. The Faraday rotation can be tuned by changing the strength of the external static magnetic field.

Nonlinear infrared transmission through and reflection off antiferromagnetic films

We present the nonlinear infrared transmission through and reflection off an antiferromagnetic film under the magnetic field. In the geometry with the anisotropy axis parallel to the film surface and normal to the plane, using TE wave obliquely incident upon the film, we find that the nonlinear modification for the transmission and reflection is very obvious, especially for the large incident angle.

Reflection and transmission by magnetic multilayers

This paper presents the formalism for transmission of normally incident electromagnetic radiation through a finite superlattice of alternating magnetic and non-magnetic layers. It is assumed that the ordering direction and static field, if any, are perpendicular to the interfaces so that the eigenmodes for propagation are the states of circular polarization. The transmission and reflection coefficients are expressed in terms of the transfer matrix for propagation across a unit cell of the superlattice. The results are illustrated for a ferromagnet/non-magnet superlattice. Prominent features are seen related first to resonances in the magnetic permeability and second to the stop bands of the Bloch waves of the superlattice. In transparency regions, fringes occur due to the overall thickness of the superlattice.

Phase diagrams of a diluted Ising ferromagnetic film with spin 1 in a transverse field

The phase transition properties of a diluted Ising ferromagnetic film with s = 1 in a transverse field are investigated and calculated within the framework of the effective-field theory. We discuss mainly the phase diagrams as well as the dependence of the critical concentration of magnetic atoms on the surface coupling constant and thickness of film. Some interesting properties are found.

Transmission by antiferromagnetic-nonmagnetic multilayers

The transmission of electromagnetic radiation at normal incidence through a finite antiferromagnetic-nonmagnetic superlattice is considered for an applied field normal to the interfaces (Faraday geometry) and for a field parallel to the interfaces (Voigt geometry). Besides the transmission spectra, we present the calculations of the dispersion curves for a relevant infinite superlattice to understand the features of the spectra. The transmission is weak or very weak at frequencies in the stop bands of the corresponding infinite superlattice, and these stop bands only appear at the Brillouin-zone edges , not at .