相关论文: Phenomenological theory of spin-orbit phase transi…
The topological theory of phase transitions was proposed on the basis of different arguments, the most important of which are: a direct evidence of the relation between topology and phase transitions for some exactly solvable models; an…
The Ginzburg-Landau Hamiltonian for incommensurate frustrated classical spin systems is analyzed. The coupling to phonons through the Dzyaloshinskii-Moriya interaction and/or the four-spin exchange interaction of the Coulomb origin under…
We consider a model of strongly correlated $e_g$ electrons interacting by superexchange orbital interactions in the ferromagnetic phase of LaMnO$_3$. It is found that the classical orbital order with alternating occupied $e_g$ orbitals has…
The order parameters of the magnetic, charge and structural orders at half-doped manganites are identified. A corresponding Landau theory of the phase transitions is formulated. Many structural and thermodynamical behaviors are accounted…
Cubic spinel GeNi2O4 exhibits intriguing magnetic properties with two successive antiferromagnetic phase transitions (TN1 12.1 and TN2 11.4 K) with the absence of any structural transition. We have performed detailed heat capacity and…
Spin-orbit coupling is a single-particle phenomenon known to generate topological order, and electron-electron interactions cause ordered many-body phases to exist. The rich interplay of these two mechanisms is present in a broad range of…
We use the Gutzwiller variational theory to investigate the electronic and the magnetic properties of fcc-Nickel. Our particular focus is on the effects of the spin-orbit coupling. Unlike standard relativistic band-structure theories, we…
Unconventional superconductivity with spin-triplet Cooper pairing is reviewed on the basis of the quasi-phenomenological Ginzburg-Landau theory. The superconductivity, in particular, the mixed phase of coexistence of ferromagnetism and…
We develop U(1) slave spin-rotor theory, suggesting a metal-metal transition from Landau's Fermi-liquid state to a bad metal phase, as U(1) slave charge-rotor theory [Phys. Rev. B {\bf 70}, 035114 (2004)] describes a metal-insulator…
Transition operator method is proposed for description of the dynamics of spectroscopic transitions. Quantum-mechanical analogue of Landau-Lifshitz equation has been derived for the system representing itself the periodical…
The magnetic properties of the double perovskite oxide $Sr_{2}$FeMo$O_{6}$ are analyzed using a mixed-spin Ising model with spins $\left( \frac{1}{2},\frac{5}{2}\right) $ in the presence of a random crystal field $\Delta$ and exchange…
The theory for disordered itinerant ferromagnets developed in a previous paper is used to construct a simple effective field theory that is capable of describing the quantum phase transition from a ferromagnetic metal to a ferromagnetic…
We study a spin $S$ quantum Heisenberg model on the Fe lattice of the rare-earth oxypnictide superconductors. Using both large $S$ and large $N$ methods, we show that this model exhibits a sequence of two phase transitions: from a high…
A systematic microscopic theory of magnetically induced ferroelectricity and lattice modulation is presented for all electron configurations of Mott-insulating transition-metal oxides. Various mechanisms of polarization are identified in…
A phenomenological theory is suggested to explain the experimentally discovered "paramagnetic peculiarity" and the unconventional change of the energetic state of a layers of high T_{c} of Y-Ba-Cu-O in the vicinity of the phase transition.…
We suggest that under an increase of a magnetic field a spin-ladder with ferromagnetic legs does not pass without fail through an incommensurate phase but possibly in a straight way turns into a fully polarized ferromagnetic phase. The spin…
Using the formalism of pseudospin and isospin operators the Hamiltonian of an effective Kugel-Khomskii model with spin-orbit coupling is derived with an exact account of the $t_{2g}$ multiplet splitting by the crystal field. An analytical…
Density functional theory (DFT) including van der Waals weak interaction in conjunction with the so called rotational invariant DFT+U, where $U$ is the Hubbard interaction of the iron site, is used to show that the fluorinated spin…
We study the classical and quantum phase transitions of Sp(4) spin systems on three dimensional stacked square and triangular lattices. We present general Ginzburg-Landau field theories for various types of Sp(4) spin orders with different…
The lack of inversion symmetry in the crystal lattice of magnetic materials gives rise to complex non-collinear spin orders through interactions of relativistic nature, resulting in interesting physical phenomena, such as emergent…