arXiv subjects

A. Kolezhuk

Publications and source records attributed to A. Kolezhuk.

3 recordsLinked to original sources

arXiv2016

On Short-Range Enhancement of Van-der-Waals Forces

We show that for nanoparticles with giant polarizability $α$ (a prominent example being the recently studied Na$_{14}$F$_{13}$ molecular clusters) van der Waals forces are significantly enhanced at interparticle distances shorter than $R_0=(α/2πε_0)^{1/3}$. For an adequate description of this phenomenon, nonlinear effects must be taken into account. We show that, contrary to some theoretical claims, an accurate treatment of nonlinearity does not lead to any repulsive forces.

cond-mat.mes-hall↗

arXiv2003

Massive triplet excitations in a magnetized anisotropic Haldane spin chain

Inelastic neutron scattering experiments on the Haldane-gap quantum antiferromagnet \nd are performed at mK temperatures in magnetic fields of almost twice the critical field $H_c$ applied perpendicular to the spin cahins. Above $H_c$ a re-opening of the spin gap is clearly observed. In the high-field Néel-ordered state the spectrum is dominated by three distinct long-lived excitation branches. Several field-theoretical models are tested in a quantitative comparison with the experimental data.

cond-mat.str-el↗

arXiv1996

Variational and DMRG studies of the Frustrated Antiferromagnetic Heisenberg S=1 Quantum Spin Chain

We study a frustrated antiferromagnetic isotropic Heisenberg $S=1$ chain using a variational ansatz and the DMRG. At $α_D=0.284(1)$, there is a disorder point of the second kind, marking the onset of incommensurate correlations in the chain. At $α_L=0.3725(25)$ there is a Lifshitz point, at which the excitation spectrum develops a doubly degenerate structure. These points are the quantum remnants of the transition from antiferromagnetic to spiral order in the classical frustrated chain. At $α_T=0.7444(6)$ there is a first order phase transition from an AKLT phase to a next-nearest neighbor generalization of the AKLT model. At the transition, the string order parameter shows a discontinuous jump of 0.085 to 0; the correlation length and the gap are both finite at the transition. The problem of edge states in open frustrated chains is discussed at length.

cond-mat↗