Density of Zeros on the Lee-Yang circle obtained from magnetization data of a two-dimensional Ising ferromagnet

TL;DR

This paper experimentally determines the density of Lee-Yang zeros on the circle for a 2D Ising ferromagnet using magnetization data, linking statistical theory with measurable magnetic properties.

Contribution

First experimental determination of Lee-Yang zeros density function from magnetization data of a real ferromagnet.

Findings

Density function g(θ) obtained from magnetization data

Magnetic specific heat matches predictions from g(θ)

In-plane exchange constant derived from analysis

Abstract

In order to provide an experimental access to the statistical theory of Lee and Yang (1952) the density function g(theta) of zeros on the Lee-Yang circle has been determined for the first time by analyzing isothermal magnetization data, m(H), of the Ising ferromagnet FeCl2 in axial magnetic fields, H, at temperatures 34 < T < 99K. The validity of our approach is demonstrated by the perfect agreement of magnetic specific heat data as calculated from g(theta) and m(H) via Maxwells relation, respectively. Moreover, the correct in-plane exchange constant of FeCl2 emerges from the series expansion of m(H) involved in the analysis.