arXiv subjects

Oleg Starykh

Publications and source records attributed to Oleg Starykh.

2 recordsLinked to original sources

arXiv2012

Bold Diagrammatic Monte Carlo technique for frustrated spin systems

Using fermionic representation of spin degrees of freedom within the Popov-Fedotov approach we develop an algorithm for Monte Carlo sampling of skeleton Feynman diagrams for Heisenberg type models. Our scheme works without modifications for any dimension of space, lattice geometry, and interaction range, i.e. it is suitable for dealing with frustrated magnetic systems at finite temperature. As a practical application we compute uniform magnetic susceptibility of the antiferromagnetic Heisenberg model on the triangular lattice and compare our results with the best available high-temperature expansions. We also report results for the momentum-dependence of the static magnetic susceptibility throughout the Brillouin zone.

cond-mat.str-el↗

arXiv1993

Quantum Antiferromagnet at Finite Temperature: A Gauge Field Approach

Starting from the $CP^{N-1}$ model description of the thermally disordred phase of the $D=2$ quantum antiferromagnet, we examine the interaction of the Schwinger-boson spin-1/2 mean-field excitations with the generated gauge (chirality) fluctuations in the framework of the 1/N expansion. This interaction dramatically supresses the one-particle motion, but enhances the staggered static susceptibility. This means that actual excitations in the system are represented by the collective spin-1 excitations, whereas one-particle excitations disappear from the problem. We also show that massive fluctuations of the constraint field are significant for the susceptibility calculations. A connection with the problem of a particle in random magnetic field is discussed.

cond-mat↗