Yang-Lee edge singularities determined from experimentalhigh-field magnetization data

Abstract

The isothermal magnetization m(H) of the metamagnet FeCl2 ismeasured in axial magnetic fields 0⩽µ0Ha⩽12 T at temperatures 34⩽T⩽53 K above theNéel temperature, where the system is essentially atwo-dimensional Ising ferromagnet. The analysis of the dataindicates experimental accessibility of the critical exponent µof the Yang-Lee edge singularities. They manifest themselves indivergences of the density functions g(θ), which quantify thedistribution of the zeros of the partition function on the Lee-Yangunit circle in the complex plane. In accordance with the hypothesisof universality, a critical exponent close to the theoreticalprediction for the two-dimensional Ising ferromagnet, µ = -1/6,is found.