Related papers: Ferromagnetic and random spin ordering in diluted …
A review is given on the theory of metal-insulator transitions (MIT) in doped semiconductors. We focus in particular on reviewing theories of their anomalous magnetic properties, which emerge from the interplay of spin and charge…
Quantum entanglement effects between the electronic spin and charge degrees of freedom are examined in an organic molecular solid, termed a dimer-Mott insulating system, in which molecular dimers are arranged in a crystal as fundamental…
Composite multiferroics are materials exhibiting the interplay of ferroelectricity, magnetism, and strong electron correlations. Typical example --- magnetic nano grains embedded in a ferroelectric matrix. Coupling of ferroelectric and…
Materials with nanoscale phase separation are considered. A system representing a heterophase mixture of ferromagnetic and paramagnetic phases is studied. After averaging over phase configurations, a renormalized Hamiltonian is derived…
We investigate the itinerant ferromagnetism using a diluted spin-fermion model, derived from a repulsive Hubbard model, where itinerant fermions are coupled antiferromagnetically to auxiliary fields in a three-dimensional simple cubic…
Murunskite (K$_2$FeCu$_3$S$_4$) is a bridging compound between the only two known families of high-temperature superconductors. It is a semiconductor like the parent compounds of cuprates, yet isostructural to metallic iron-pnictides.…
Substituting magnetic ions with nonmagnetic ions is a new way to study dilution. Using determinant quantum Monte Carlo calculations, we investigate an interacting Dirac fermion model with the on-site Coulomb repulsion being randomly zero on…
We study a 3-dimensional Ising model in which the tendency to order due to short-range ferromagnetic interactions is frustrated by competing long-range (Coulombic) interactions. Complete ferromagnetic ordering is impossible for any nonzero…
The influence of dilution with non--magnetic impurities on the order in the ground state of the $S=1/2$ Heisenberg antiferromagnet is investigated by Quantum Monte Carlo simulations. Data of the spin correlation functions and thermodynamic…
The electronic structure of diluted magnetic semiconductors is studied, especially focusing on the hole character. The Haldane-Anderson model is extend to a magnetic impurity, and is analyzed in the Hartree-Fock approximation. Due to the…
The magnetic properties of dilute magnetic semiconductors (DMS) are calculated from first-principles by mapping the ab initio results on a classical Heisenberg model. It is found that the range of the exchange interaction in (Ga, Mn)N is…
We consider a modified version of the one-dimensional Hubbard model, the t1-t2 Hubbard chain, which includes an additional next-nearest-neighbor hopping. It has been shown that at weak coupling this model has a Luttinger liquid phase or a…
We study crystal melting in two-dimensional antiferromagnets, by analyzing the statistical mechanics of the six-state clock model on a lattice in which defects (dislocations and disclinations) are allowed to appear. We show that the…
In the framework of the generalized mean field theory, conditions for arising the ferromagnetic state in a two-dimensional diluted magnetic semiconductor and the features of that state are defined. RKKY-interaction of magnetic impurities is…
The competition between spin glass, ferromagnetism and Kondo effect is analysed here in a Kondo lattice model with an inter-site random coupling $J_{ij}$ between the localized magnetic moments given by a generalization of the Mattis model…
We consider a disordered system of gapless fermions interacting with a singular transverse (2+1)-dimensional gauge-field. We study quantum corrections to fermion conductivity and show that they are very different from those in a Fermi…
The magnetic phase transition is experimentally known to give rise to an anomalous temperature-dependence of the electron resistivity in ferromagnetic crystals. Phenomenological theories based on the interaction between itinerant electron…
We consider superconductivity nucleation in multiply connected mesoscopic samples such as thin-walled cylinders or rings placed in electrical contact with a ferromagnet. The superconducting critical temperature and order parameter structure…
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…
By measuring electron tunneling between a ferromagnet and individual energy levels in an aluminum quantum dot, we show how spin-resolved quantum states can be used as filters to determine spin-dependent tunneling rates. We also observe…