Physical review. B, Condensed matter
Privman-Fisher hypothesis on finite systems: Verification in the case of the spherical model of ferromagnetism
Surjit Singh, Raj K. Pathria
Abstract
The Privman-Fisher hypothesis on the singular part of the free-energy density of a finite system, near the bulk critical point T=${T}_{c}$, is examined in the context of the spherical model of ferromagnetism. A d-dimensional hypercubical lattice (of size ${N}_{1}$a\ifmmode\times\else\texttimes\fi{}${N}_{2}$a\ifmmode\times\else\texttimes\fi{}...\ifmmode\times\else\texttimes\fi{}${N}_{d}$a) is considered and, subject to periodic boundary conditions, explicit expressions are derived for the free energy, the specific heat, and the magnetic susceptibility of the system at temperatures close to ${T}_{c}$. The relevant scaling functions governing the critical behavior of the system are obtained and, with the use of the asymptotic properties of these functions, various predictions of the Privman-Fisher hypothesis are verified. By implication, the passage of the given system towards standard bulk behavior, as ${N}_{j}$\ensuremath{\rightarrow}\ensuremath{\infty}, is also elucidated.