相关论文: Exponent 1/4 from the mean field approximation
A novel mean-field approximation for quasi-one-dimensional (Q1D) quantum magnets is formulated. Our new mean-field approach is based on the Bethe-type effective-field theory, where thermal and quantum fluctuations between the…
The results of extensive histogram cluster heat-bath Monte Carlo simulations on the critical behavior of the quasi-one dimensional Ising antiferromagnet on a stacked triangular lattice are presented. A small applied field is shown to induce…
Atomistic spin model simulations are immensely useful in determining temperature dependent magnetic prop- erties, but are known to give the incorrect dependence of the magnetization on temperature compared to exper- iment owing to their…
Assumption of certain hierarchy of soft ferromagnet energy terms, realized in small enough flat nano-elements, allows to obtain explicit expressions for their magnetization distributions. By minimising the energy terms sequentially, from…
We present a non mean-field model which undergoes a magnetostriction phase transition in the temperature. That is, the crystal becomes sharply contracted and magnetized once the temperature passes below the critical value
We develop an effective low-frequency theory of the electromagnetic field in equilibrium with thermal objects. The aim is to compute thermal magnetic noise spectra close to metallic microstructures. We focus on the limit where the material…
The dynamical mean field method is used to calculate the frequency and temperature dependent conductivity of dilute magnetic semiconductors. Characteristic qualitative features are found distinguishing weak, intermediate, and strong…
We present a mean field theory of ferromagnetism in diluted magnetic semiconductor quantum wells. When subband mixing due to exchange interactions between quantum well free carriers and magnetic impurities is neglected, analytic result can…
We consider a bipartite mean-field model in which both the interaction constant and the external field take different values only depending on the groups particles belong to. We compute the exact value of the thermodynamic limit of the…
Periodic boundary conditions are applied to a ferromagnetic spin lattice. A symmetrical lattice and its contributions all over space are being used. Results, for the Ising model with ferromagnetic interaction that decays as a $1/r^{D+\nu}$…
The temperature dependence of conductance resonances is used to measure the evolution with the magnetic field of the average level spacing $\Delta\epsilon$ of a droplet containing $\sim 30$ electrons created by lateral confinement of a…
We report magnetization and specific heat measurements in the 2D frustrated spin-1/2 Heisenberg antiferromagnet Cs2CuCl4 at temperatures down to 0.05 K and high magnetic fields up to 11.5 T applied along a, b and c-axes. The low-field…
Inhomogeneous distribution of the pinning force in superconductor results in a magnetization asymmetry. A model considering the field distribution in superconductor was developed and symmetric and asymmetric magnetization loops of porous…
We have studied the pressure dependence of the magnetization of single crystalline CeSi_1.81. At ambient pressure ferromagnetism develops below T_C = 9.5 Below ~ 5 K an additional shoulder in low-field hysteresis loops and a metamagnetic…
We present a laboratory electromagnet capable of generating magnetic fields up to $\pm$0.48T, specifically designed as a perpendicular flux source for thin film samples in an ambient environment. The magnet features a 250mm diameter clear…
We have studied the magnetization process of the new insulating ferromagnetic semiconductor (Al,Fe)Sb by means of x-ray magnetic circular dichroism. For an optimally doped sample with 10% Fe, a magnetization was found to rapidly increase at…
The electromagnetic properties of superconductors near a ferromagnetic instability are investigated by means of a generalized Ginzburg-Landau theory. It is found that the magnetic flux expulsion capability of the superconductor gets…
We analyze in some detail a recently proposed transfer matrix mean field approximation which yields the exact critical point for several two dimensional nearest neighbor Ising models. For the square lattice model we show explicitly that…
We derive finite temperature expansions for relativistic fermion systems in the presence of background magnetic fields, and with nonzero chemical potential. We use the imaginary-time formalism for the finite temperature effects, the…
Based on renormalization group arguments we establish that for a superconductor in the presence of a weak external magnetic field, $B$, the dependence on $B$ and the deviation from the critical temperature, $\tau$, of a thermodynamic…