Related papers: Interplay between Lattice Distortion and Spin-Orbi…
The Heisenberg-Kitaev (HK) model on the triangular lattice is conceptually interesting for its interplay of geometric and exchange frustration. HK models are also thought to capture the essential physics of the spin-orbital entanglement in…
We study the zero-temperature phase diagram of a square-lattice $S=1/2$ Heisenberg antiferromagnet with two types of regularly distributed nearest-neighbor exchange constants, $J_1>0$ (antiferromagnetic) and $-\infty < J_2 < \infty $, using…
The spin-$1/2$ Heisenberg chain with a ferromagnetic first-neighbor exchange coupling $J_1$ and an antiferromagnetic second-neighbor $J_2$ has a Haldane dimer ground state with an extremely small spin gap. Thus, the ground state is readily…
We present a model of equal spin $s_1$ dimer single molecule magnets. The spins within each dimer interact via the Heisenberg and the most general set of four quadratic anisotropic spin interactions with respective strengths $J$ and…
We study a two-orbital spin model to describe (pi,0) stripe antiferromagnetism in the iron pnictides. The "double-spin" model has an on-site Hunds's coupling and inter-site interactions extending to second neighbors (inter- and…
Electron spin resonance experiments in the quasi-1D S=1/2 antiferromagnet K$_2$CuSO$_4$Cl$_2$ reveal opening of a gap in absence of magnetic ordering, as well as an anisotropic shift of the resonance magnetic field. These features of…
We have studied the magnetic properties and spin-dynamics of the structurally-ordered double perovskite Sr$_2$CoOsO$_6$. Our neutron diffraction, muon spin relaxation and ac-susceptibility measurements reveal two antiferromagnetic (AFM)…
The effective quantum pseudospin-1/2 model for interacting rare-earth magnetic moments, which are locally described with atomic doublets, is studied theoretically for magnetic pyrochlore oxides. It is derived microscopically for localized…
We study the field dependence of the antiferromagnetic spin-1/2 Heisenberg model on the square lattice by means of exact diagonalizations. In a first part, we calculate the spin-wave velocity, the spin-stiffness, and the magnetic…
We study the spin 1/2 quantum Heisenberg antiferromagnet on a Bethe lattice diluted to the percolation threshold. Dilution creates areas of even/odd sublattice imbalance resulting in "dangling spins" (L. Wang and A. W. Sandvik, Phys. Rev.…
Disordered quantum antiferromagnets in two-dimensional compounds have been a focus of interest in the last years due to their exotic properties. However, with very few exceptions, the ground states of the corresponding Hamiltonians are…
Dielectric study on Ca3Mn2O7 features relaxor-like segmented dynamics below the antiferromagnetic ordering. Dipolar relaxations of different origin are spectrally resolved exhibiting distinct H-field alterations. This identifies their…
A model for a Heisenberg antiferromagnet on a pyrochlore lattice with exchange and dipole-dipole interactions is studied via mean-field theory. In treating the dipoles by use of the Ewald method, a soft (critical) mode with a unique…
We study the emergence of altermagnetism from repulsive interactions for electrons on the Lieb lattice as a model of quasi-2D oxychalcogenides with the so-called "anti-CuO$_{2}$" lattice structure. A comprehensive study of the Lieb lattice…
We study a spin-1/2 system with Heisenberg plus ring exchanges on a four-leg triangular ladder using the density matrix renormalization group and Gutzwiller variational wave functions. Near an isotropic lattice regime, for moderate to large…
We present a powder inelastic neutron scattering study of magnetic excitations in Ba$_2$FeReO$_6$, a member of the double perovskite family of materials which exhibit half-metallic behavior and high Curie temperatures. We find clear…
Double perovskites Sr2FeOsO6 and Ca2FeOsO6 show puzzling magnetic properties, the former a low-temperature antiferromagnet while the later a high-temperature insulating ferrimagnet. Here, in order to understand the underlying mechanism, we…
Time-of-flight inelastic neutron scattering measurements have been carried out on polycrystalline samples of the 4$d^3$ and 5$d^3$ double pervoskite antiferromagnets La$_2$LiRuO$_6$ and La$_2$LiOsO$_6$. These reveal the development of an…
Quantum magnetic properties in a geometrically frustrated lattice of spin-1/2 magnet, such as quantum spin liquid or solid and the associated spin fractionalization, are considered key in developing a new phase of matter. The feasibility of…
We report the magnetic susceptibility and the low-temperature specific heat of a double perovskite compound, Sr2CuTeO6, which is expected as the spin-1/2 square-lattice Heisenberg antiferromagnet with nearest-neighbor J1 and…