3 research outputs found
Application of Minimal Subtraction Renormalization to Crossover Behavior near the He Liquid-Vapor Critical Point
Parametric expressions are used to calculate the isothermal susceptibility,
specific heat, order parameter, and correlation length along the critical
isochore and coexistence curve from the asymptotic region to crossover region.
These expressions are based on the minimal-subtraction renormalization scheme
within the model. Using two adjustable parameters in these
expressions, we fit the theory globally to recently obtained experimental
measurements of isothermal susceptibility and specific heat along the critical
isochore and coexistence curve, and early measurements of coexistence curve and
light scattering intensity along the critical isochore of He near its
liquid-vapor critical point. The theory provides good agreement with these
experimental measurements within the reduced temperature range
Surface critical behavior in fixed dimensions : Nonanalyticity of critical surface enhancement and massive field theory approach
The critical behavior of semi-infinite systems in fixed dimensions is
investigated theoretically. The appropriate extension of Parisi's massive field
theory approach is presented.Two-loop calculations and subsequent Pad\'e-Borel
analyses of surface critical exponents of the special and ordinary phase
transitions yield estimates in reasonable agreement with recent Monte Carlo
results. This includes the crossover exponent , for which we obtain
the values and , considerably
lower than the previous -expansion estimates.Comment: Latex with Revtex-Stylefiles, 4 page
Quantum phase transitions and thermodynamic properties in highly anisotropic magnets
The systems exhibiting quantum phase transitions (QPT) are investigated
within the Ising model in the transverse field and Heisenberg model with
easy-plane single-site anisotropy. Near QPT a correspondence between parameters
of these models and of quantum phi^4 model is established. A scaling analysis
is performed for the ground-state properties. The influence of the external
longitudinal magnetic field on the ground-state properties is investigated, and
the corresponding magnetic susceptibility is calculated. Finite-temperature
properties are considered with the use of the scaling analysis for the
effective classical model proposed by Sachdev. Analytical results for the
ordering temperature and temperature dependences of the magnetization and
energy gap are obtained in the case of a small ground-state moment. The forms
of dependences of observable quantities on the bare splitting (or magnetic
field) and renormalized splitting turn out to be different. A comparison with
numerical calculations and experimental data on systems demonstrating magnetic
and structural transitions (e.g., into singlet state) is performed.Comment: 46 pages, RevTeX, 6 figure