arXiv subjects

Mikhail Kiselev

Publications and source records attributed to Mikhail Kiselev.

21 records · Page 2Linked to original sources

arXiv2014

Critical Exponents of the Superfluid-Bose Glass Transition in Three-Dimensions

Recent experimental and numerical studies of the critical-temperature exponent $ϕ$ for the superfluid-Bose glass universality in three-dimensional systems report strong violations of the key quantum critical relation, $ϕ=νz$, where $z$ and $ν$ are the dynamic and correlation length exponents, respectively, and question the fundamental concepts underlying quantum critical phenomena. Using Monte Carlo simulations of the disordered Bose-Hubbard model, we demonstrate that previous work on the superfluid-to-normal fluid transition-temperature dependence on chemical potential (or magnetic field, in spin systems), $T_c \propto (μ-μ_c)^ϕ$, was misinterpreting transient behavior on approach to the fluctuation region with the genuine critical law. When the model parameters are modified to have a broad quantum critical region, simulations of both quantum and classical models reveal that the $ϕ=νz$ law [with $ϕ=2.7(2)$, $z=3$, and $ν= 0.88(5)$] holds true, resolving the $ϕ$-exponent "crisis".

cond-mat.str-el↗

arXiv2014

Equilibrium Fermi-liquid coefficients for the fully screened N-channel Kondo model

We analytically and numerically compute three equilibrium Fermi-liquid coefficients of the fully screened $N$-channel Kondo model, namely $c_B$, $c_T$ and $c_\varepsilon$, characterizing the magnetic field and temperature dependence of the resisitivity, and the curvature of the equilibrium Kondo resonance, respectively. We present a compact, unified derivation of the $N$-dependence of these coefficients, combining elements from various previous treatments of this model. We numerically compute these coefficients using the numerical renormalization group, with non-Abelian symmetries implemented explicitly, finding agreement with Fermi-liquid predictions on the order of 5% or better.

cond-mat.str-el↗

arXiv2011

Phase Diagram of Commensurate Two-Dimensional Disordered Bose Hubbard Model

We establish the full groundstate phase diagram of disordered Bose-Hubbard model in two-dimensions at unity filling factor via quantum Monte Carlo simulations. Similarly to the three-dimensional case we observe extended superfluid regions persisting up to extremely large values of disorder and interaction strength which, however, have small superfluid fractions and thus low transition temperatures. In the vicinity of the superfluid--insulator transition of the pure system, we observe an unexpectedly weak---almost not resolvable---sensitivity of the critical interaction to the strength of (weak) disorder.

cond-mat.other↗