Related papers: Ordering in spatially anisotropic triangular antif…
We study S=1 kagome antiferromagnets with isotropic Heisenberg exchange $J$ and strong easy axis single-ion anisotropy $D$. For $D \gg J$, the low-energy physics can be described by an effective $S=1/2$ $XXZ$ model with antiferromagnetic…
The one-dimensional spin-1/2 $XXZ$ model in a mixed transverse and longitudinal magnetic field is studied. Using the specially developed version of the mean-field approximation the order-disorder transition induced by the magnetic field is…
We discuss the role of quantum fluctuations in Heisenberg antiferromagnets on face-centered cubic lattice with small dipolar interaction in which the next-nearest-neighbor exchange coupling dominates over the nearest-neighbor one. It is…
The magnetization process of the one-dimensional antiferromagnetic Heisenberg model with the Ising-like anisotropic exchange interaction is studied by the exact diagonalization technique. It results in the evidence of the first-order spin…
We study a frustrated 3D antiferromagnet of stacked $J_1 - J_2$ layers. The intermediate 'quantum spin liquid' phase, present in the 2D case, narrows with increasing interlayer coupling and vanishes at a triple point. Beyond this there is a…
The strong coupling phase diagram of the spinless fermions on the anisotropic triangular lattice at half-filling is presented. The geometry of inter-site Coulomb interactions rules the phase diagram. Unconventional charge ordered phases are…
Geometrical frustration and the enhancement of strong quantum fluctuations in two-dimensional triangular antiferromagnets can lead to various intriguing phenomena. Here, we studied the spin-1/2 triangular lattice antiferromagnet…
Selection of the ground state of the kagom\'e-lattice $XXZ$ antiferromagnet by quantum fluctuations is investigated by combining non-linear spin-wave and real-space perturbation theories. The two methods unanimously favor ${\bf q}=0$ over…
We present Quantum Monte-Carlo simulations of an exchange-anisotropic spin-1/2 Heisenberg model on a square lattice with nearest and next-nearest neighbor interactions. The ground state phase diagram shows two classical magnetically ordered…
The ground-state phase diagram of a spin-1/2 XXZ chain with competing ferromagnetic nearest-neighbor (J_1<0) and antiferromagnetic second-neighbor (J_2>0) exchange couplings is studied by means of the infinite time evolving block decimation…
The double exchange model describing interactions of itinerant electrons with localized spins is usually used to explain ferromagnetism in metals. We show that for a variety of crystal lattices of different dimensionalities and for a wide…
We study quantum antiferromagnetism on the highly frustrated checkerboard lattice, also known as the square lattice with crossings. The quantum Heisenberg antiferromagnet on this lattice is of interest as a two-dimensional analog of the…
The quantum spin-1/2 antiferromagnetic Heisenberg model on a two dimensional triangular lattice geometry with spatial anisotropy is relevant to describe materials like ${\rm Cs_2 Cu Cl_4}$ and organic compounds like…
Anisotropic antiferromagnetic systems of dimensionality greater than one in an external field are shown to exhibit a complicated array of ground states depending on the spin structure of the surface. The simplest structure that exhibits…
Zero-point quantum fluctuations of a N\'eel order can produce effective interactions between quasi-orphan spins weakly coupled to the lattice. On the $\sqrt{3}\times\sqrt{3}-$distorted triangular lattice, this phenomenon leads to a…
We uncover four new spin-charge ordered ground states in the strong coupling limit of the Kondo lattice model on triangular geometry. Two of the states at one-third electronic filling ($n=1/3$) consist of decorated ferromagnetic chains…
Using the coupled-cluster method (CCM) and the rotation-invariant Green's function method (RGM), we study the influence of the interlayer coupling $J_\perp$ on the magnetic ordering in the ground state of the spin-1/2 $J_1$-$J_2$ frustrated…
We study the phase diagram and multicritical behavior of anisotropic Heisenberg antiferromagnets on a square lattice in the presence of a magnetic field along the easy axis. We argue that, beside the Ising and XY critical lines, the phase…
We theoretically study the spatially anisotropic spin-1/2 kagome antiferromagnet with Dzyaloshinskii-Moriya (DM) interaction using a renormalization group analysis in the quasi-one-dimensional limit. We identify the various temperature and…
We study possible paramagnetic phases of antiferromagnets on the Shastry-Sutherland lattice by a gauge-theoretic analysis of fluctuations in a theory with Sp(2N) symmetry. In addition to the familiar dimer phase, we find a confining phase…