Direct observation of momentum-dependent exchange interaction in a heisenberg ferromagnet.

Thermodynamics of a two-dimensional Heisenberg ferromagnet with dipolar interaction

Analyticity Properties of the Anisotropic Heisenberg Model

An upper bound Te for the critical temperature of a class of spin systems which includes the Heisenberg ferromagnet is derived. The analyticity of the free energy as a function of the temperature, the external magnetic field, and the interaction potentials, is demonstrated in a domain which includes all temperatures T > Tc For the isotropic Heisenberg ferromagnet in v dimensions we find the poo...

A Dynamical Formulation of the Aharonov-bohm Effect

In 1969 Aharonov, Pend leton and Petersen introduced a new dynamical variable, the modular momentum, and discussed how several nonlDcal interactions could be characterized as resulting from its exchange. In this paper we review and extend their approach by applying it to the Aharonov~Bohm effect with an electromagnetic scalar potential. First we review the nonclassical nature of the effect, sho...

Impact of momentum on stock returns in different market conditions

The purpose of this study is to compare the impacts of momentum on stock returns of companies listed in Tehran Stock Exchange in different market conditions. For this purpose, the sample size is 120 months from 2008 to 2017. The research hypotheses are estimated using multivariate linear regression using time series method. Based on the results of the hypotheses test, the momentum in each of th...

Dynamic Phase transitions in ferromagnetic systems : Some new phenomena

The thermodynamical behaviours of ferromagnetic systems in equilibrium are well studied. However, the ferromagnetic system, far from equilibrium, became an interesting field of research in last few decades. The ferromagnetic systems in the presence of a steady magnetic field are also studied by using standard tools of equilibrium statistical physics. The ferromagnet in the presence of time depe...