Year: 2000
Type: article
Abstract: The specific heat ${(C}_{m})$ and optical birefringence $(\ensuremath{\Delta}n)$ for the magnetic percolation threshold system ${\mathrm{Fe}}_{0.25}{\mathrm{Zn}}_{0.75}{\mathrm{F}}_{2}$ are analyzed with the aid of Monte Carlo (MC) simulations. Both $\ensuremath{\Delta}n$ and the magnetic energy ${(U}_{m})$ are governed by a linear combination of near-neighbor spin-spin correlations, which we have determined for $\ensuremath{\Delta}n$ using MC simulations modeled closely after the real system. Near a phase transition or when only one interaction dominates, the temperature derivative of the birefringence $[d(\ensuremath{\Delta}n)/dT]$ is expected to be proportional to ${C}_{m}$ since all relevant correlations necessarily have the same temperature dependence. Such a proportionality does not hold for ${\mathrm{Fe}}_{0.25}{\mathrm{Zn}}_{0.75}{\mathrm{F}}_{2}$ at low temperatures, however, indicating that neither condition above holds. MC results for this percolation system demonstrate that the shape of the temperature derivative of correlations associated with the frustrating third-nearest-neighbor interaction differs from that of the dominant second-nearest-neighbor interaction, accurately explaining the experimentally observed behavior quantitatively.
Authors: W. C. Barber, D. P. Belanger
Institution: University of California, Santa Cruz
Language: Latvian
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W1636983753