Related papers: Ordering and criticality in an underscreened Kondo…
A magnetic moment in a metal or in a quantum dot is, at low temperatures, screened by the conduction electrons through the mechanism of the Kondo effect. This gives rise to spin-spin correlations between the magnetic moment and the…
We investigate approximate emergent nonabelian symmetry in a class of weakly first order `deconfined' phase transitions using Monte Carlo simulations and a renormalization group analysis. We study a transition in a 3D classical loop model…
We use an estimator of quantum criticality based on the entanglement entropy to discuss the ground state properties of the 1D anisotropic Kondo necklace model. We found that the T=0 phase diagram of the model is described by a critical line…
We investigate the magnetic order and related strongly-correlated effects in an one-dimensional Ising-Kondo lattice with transverse field. This model is the anisotropic limit of the conventional isotropic Kondo lattice model, in the sense…
We present elastic and quasielastic neutron scattering measurements characterizing peculiar short-range charge-orbital and spin order in the layered perovskite material La1.5Sr0.5CoO4. We find that below Tc~750 K holes introduced by Sr…
We consider a two-layer Heisenberg antiferromagnet which can be either in the N\'{e}el-ordered or in the disordered phase at $T=0$, depending on the ratio of the intra- and interlayer exchange constants. We reduce the problem to an…
Recently there has been a resurgence of intense experimental and theoretical interest on the Kondo physics of nanoscopic and mesoscopic systems due to the possibility of making experiments in extremely small samples. We have carried out…
The ground state phase diagram of a spin $S=1/2$ $XXZ$ Heisenberg chain with spatially modulated Dzyaloshinskii-Moriya (DM) interaction $ {\cal H}= \sum_n J\left[\left(S^x_n S^x_{n+1} +S^y_n S^y_{n+1}+\Delta S^z_n…
The ordering of weakly coupled random antiferromagnetic $S=1/2$ chains, as relevant for recent experimentally investigated spin chain materials, is considered theoretically. The one-dimensional isotropic Heisenberg model with random…
A scaling theory of the Kondo lattices with frustrated exchange interactions is developed, criterium of antiferromagnetic ordering and quantum-disordered state being investigated. The calculations taking into account magnon and incoherent…
We study the S>1 nearest-neighbor Heisenberg model with a ferromagnetic interaction J and a large non-collinear <111> easy-axis anisotropy D on a pyrochlore lattice. For a finite D>>|J|, the low-energy physics is described by a < 111 >…
Quantum fluctuations originating phase competition or geometrical frustration of spins lead to novel states such as a quantum critical point and a quantum spin liquid where the strong quantum fluctuations suppress any ordered states even at…
Co$_3$Sn$_2$S$_2$ has recently been predicted to be a Weyl semimetal in which magnetic order is key to its behavior as a topological material. Here we report unpolarized neutron diffraction and spherical neutron polarimetry measurements,…
Spin-nematic and spin-smectic phases have been reported in magnetic materials, which break rotational symmetry while preserving translational symmetry along certain directions. However, until now the analogy to liquid crystals remained…
The phase diagram of the two-leg Kondo ladder is investigated using computational techniques. Ferromagnetism is present, but only at small conduction electron densities and robust Kondo coupling $J$. For densities $n\gtrsim0.4$ and any…
A frustrated spin-$1/2$ XXZ chain model comprising a ferromagnetic nearest-neighbor coupling with the bond alternation, $J_1(1\pm\delta)<0$, and an antiferromagnetic second-neighbor exchange coupling $J_2>0$ is studied at zero and weak…
Phases of matter are conventionally characterized by order parameters describing the type and degree of order in a system. For example, crystals consist of spatially ordered arrays of atoms, an order that is lost as the crystal melts. Like-…
We examine critically two different recently proposed models of charge ordering in the nominally 1/4-filled organic charge transfer solids (CTS). In one dimension, the two models are characterized by site charge densities of the form…
We have studied spin density wave (SDW) phase transitions in dimerized quarter-filled Hubbard chains weakly coupled via interchain one-particle hopping, $t_{b0}$. It is shown that there exists a critical value of $t_{b0}$, $t_{b}^\ast$,…
We use neutron scattering to study the spin and charge/orbital ordering (CO-OO) in the nearly half-doped perovskite manganite $Pr_{0.55}(Ca_{0.8}Sr_{0.2})_{0.45}MnO_3$ (PCSMO). On cooling from room temperature, PCSMO first enters into a…