Related papers: Order from disorder in the double-exchange model
We study the competition of magneto-dipole, anisotropy and exchange interactions in composite three dimensional multiferroics. Using Monte Carlo simulations we show that magneto-dipole interaction does not suppress the ferromagnetic state…
We consider a recently introduced 2-D square-to-rectangle martensite model that explains several unusual features of martensites to study ferromagnetic martensites. The strain order parameter is coupled to the magnetic order parameter…
In this paper we present results on the disordered Holstein-Double Exchange model, explicitly in three dimension and `metallic' densities, obtained by using a recently developed Monte Carlo approach. Following up on our earlier paper,…
We present systematic theoretical investigations to explore the microscopic mechanisms leading to the formation of antiferromagnetism in Ru2MnZ (Z= Sn,Sb,Ge,Si) full Heusler alloys. Our study is based on first-principles calculations of…
The current theoretical and experimental situations are reviewed for low-dimensional insulating systems with a low magnetic transition temperature TM and pronounced short-range magnetic order above this temperature. Both the standard and…
We study the effects of temperature and magnetic field on a two-orbital Hubbard model within dynamical mean field theory. We focus on the quarter filled system, which is a special point in the phase diagram due to orbital degeneracy. At…
The interplay between quantum and thermal fluctuations in the presence of quenched random disorder is a long-standing open theoretical problem which has been made more urgent by advances in modern experimental techniques. The fragility of…
The question of the existence of order in two-dimensional isotropic dipolar Heisenberg antiferromagnets is studied. It is shown that the dipolar interaction leads to a gap in the spin-wave energy and a nonvanishing order parameter. The…
Magnetic order is usually associated with well-defined magnon excitations. Exotic magnetic fluctuations with fractional, topological or multipolar character, have been proposed for radically different forms of magnetic matter such as…
We consider electron pairing in a two-dimensional thermally disordered itinerant anti-ferromagnet. It is shown that transverse spin fluctuations in such a state can give rise to superconductivity with a sizeable critical temperature $T_c$.…
We present results of a numerical mean field treatment of interacting spins and carriers in doped diluted magnetic semiconductors, which takes into account the positional disorder present in these alloy systems. Disorder is found to enhance…
We identify the bosonic excitations in ferroelectrics that carry electric dipoles from the phenomenological Landau-Ginzburg-Devonshire theory. The "ferron" quasi-particles emerge from the concerted action of anharmonicity and broken…
A double exchange model with quenched disorder for conduction electrons is studied by field theoretical methods. By using a path integral formalism and replica techniques based on it, an ensemble-averaged spin wave dispersion of the…
We study the two-dimensional periodic Anderson model at half-filling using quantum Monte Carlo (QMC) techniques. The ground state undergoes a magnetic order-disorder transition as a function of the effective exchange coupling between the…
It is shown how the exchange interaction, the dipole-dipole interaction, and the Dzyaloshinsky-Moriya interaction between electronic spin-density fluctuations emerge naturally from a field-theoretic framework that couples electrons to the…
The competition between the magnetic and charge orderings in a model cuprate is considered in terms of a simplified static 2D spin-pseudospin model. This model is equivalent to the 2D dilute antiferromagnetic (AFM) Ising model with charged…
From first principles, we calculate the Heisenberg interactions between neighboring dimers in several compounds within the Et$_{n}$Me$_{4-n}X$[Pd(dmit)$_2$]$_2$ (Et = ethyl, Me = methyl, dmit = 2-thioxo-1,3-dithiole-4,5-dithiolate) family…
Density functional theory in the local or semi-local density approximation is a powerful tool for materials simulation, yet it struggles in many cases to describe collective electronic order that is driven by electronic interactions. In…
An effective field theory is derived for the ferromagnetic transition of diffusive electrons at T=0. The static disorder which leads to diffusive electron dynamics induces an effective long-range interaction between the spins of the form…
Effect of biquadratic exchange on phase transitions of a planar classical Heisenberg (or XY) ferromagnet on a stacked triangular lattice is investigated by Standard Monte Carlo and Histogram Monte Carlo simulations in the region of a…