English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The spin-spin correlation function of the 2D XY model decays as a power lawat all temperatures below the Berezinskii-Kosterlitz-Thouless transition pointwith a temperature dependent exponent $\eta=\eta(T/J)$ ($J$ is theferromagnetic coupling strength). It is known from computer experiments that inthe 2D XY model with site or bond dilution this exponent depends onconcentration $p$ of removed sites/bonds as well. Knowing the slope$\partial\eta/\partial p$ at point $p=0$, one can predict the value of theexponent for small dilution concentrations:$\eta(p)\simeq\eta(0)+p(\partial\eta/\partial p)|_{p=0}$. As it is shown inthis paper, the spin-wave Hamiltonian allows to obtain exact results for thisslope: $(\partial\eta/\partial p)|_{p=0} = T/(2J) + O((T/J)^2)$ and $T/(\pi J)+ O((T/J)^2)$ for site and for bond dilution, respectively.

Spin-spin correlation function of the 2D XY model with weak site or bond dilution