Related papers: Two-dimensional S=1/2 antiferromagnet on a plaquet…
Electronic structure calculations of the Verwey ground state of magnetite, Fe3O4, using density functional theory with treatment of on-site Coulomb interactions (DFT+U scheme) are reported. These calculations use the recently-published…
Two triangular lattice antiferromagnets Sr$_3$Co(Nb,Ta)$_2$O$_9$ with an effective $j_{\rm eff}=1/2$ of Co$^{2+}$ are synthesized and their magnetic properties are investigated via magnetization and heat capacity measurements. The leading…
We consider a class of one-dimensional Heisenberg spin models (plaquette chains) related to the recently found 1/5-depleted square-lattice Heisenberg system $CaV_4O_9$. A number of exact and exact-numerical results concerning the properties…
By using a variational Monte Carlo technique based upon Gutzwiller-projected fermionic states, we investigate the dynamical structure factor of the antiferromagnetic $S=1/2$ Heisenberg model on the honeycomb lattice, in presence of…
The zero-temperature phase diagrams of a two-dimensional frustrated quantum antiferromagnetic system, namely the Union Jack model, are studied using the coupled cluster method (CCM) for the two cases when the lattice spins have spin quantum…
Novel competing orders are found in spin 3/2 cold atomic systems in one-dimensional optical traps and lattices. In particular, the quartetting phase, a four-fermion counterpart of Cooper pairing, exists in a large portion of the phase…
We study phase domain coarsening in the long time limit after a quench of magnetic field in a quasi one-dimensional spin-1 antiferromagnetic condensate. We observe that the growth of correlation length obeys scaling laws predicted by the…
We study the spin-1/2 Heisenberg model in a lattice that interpolates between the triangular and the kagome lattices. The exchange interaction along the bonds of the kagome lattice is J, and the one along the bonds connecting kagome and…
The phase diagram of the quasi-two-dimensional easy-plane antiferromagnetic model, with a magnetic field applied in the easy plane, is studied using the self-consistent harmonic approximation. We found a linear dependence of the transition…
Neutron diffraction on the double perovskite Sr2YRuO6 with a quasi-face-centered cubic (FCC) lattice of Ru moments reveals planar magnetic correlations that condense into a partial long-range ordered state with coupled alternate…
The study of interacting spin systems is of fundamental importance for modern condensed matter physics. On frustrated lattices, magnetic exchange interactions cannot be simultaneously satisfied, and often give rise to competing exotic…
We present a rigorous proof of an ordering transition for a two-component two-dimensional antiferromagnet with nearest and next-nearest neighbor interactions. The low-temperature phase contains two states distinguished by local order among…
The two-dimensional Kondo lattice model with both nearest and next-nearest neighbor exchange interactions is studied within a mean-field approach and its phase diagram is determined. In particular, we allow for lattice translation symmetry…
The magnetic ground state and the crystalline electric field level scheme of the triangular lattice antiferromagnet KCeO$_2$ are investigated. Below $T_N =$ 300 mK, KCeO$_2$ develops signatures of magnetic order in specific heat…
We numerically study quantum magnetism of ultra-cold alkali and alkaline-earth fermion systems with large hyperfine spin $F=3/2$, which are characterized by a generic $Sp(N)$ symmetry with N=4. The methods of exact diagonalization (ED) and…
Large spin systems can exhibit unconventional types of magnetic ordering different from the ferromagnetic or N\'eel-like antiferromagnetic order commonly found in spin 1/2 systems. Spin-nematic phases, for instance, do not break…
The phase transition of the quantum spin-1/2 frustrated Heisenberg antiferroferromagnet on an anisotropic square lattice is studied by using a variational treatment. The model is described by the Heisenberg Hamiltonian with two…
We discuss the thermodynamic and magnetic properties of a competing high-spin/low-spin two-orbital two-electron model on a square-lattice possibly relevant to the nickelates such as Ba$_2$NiO$_2$(AgSe)$_2$ (BNOAS). We focus on parameter…
Neutron diffraction and nuclear quadrupole resonance (NQR) measurements were employed to investigate magnetic order in the non-ferroelectric phase preceding the low-temperature multiferroic state in FeTe2O5Br. Refnement of the neutron…
We investigate the phase diagram of a generalized spin-1/2 quantum antiferromagnet on a ladder with rung, leg, diagonal, and ring-exchange interactions. We consider the exactly soluble models associated with the problem, obtain the exact…