Department of Physics and Astronomy: Publications and Other Research


Date of this Version

December 1998


Published by American Physical Society. Copyright 1998. Permission to use. Phys. Rev. Lett. 81, 5644 (1998).


In order to provide experimental access to the statistical theory of Lee and Yang [Phys. Rev. 87, 410 (1952)] the density function g(θ) 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≤99 K. The validity of our approach is demonstrated by the perfect agreement of magnetic specific heat data as calculated from g(θ) and m(H) via Maxwell's relation. Moreover, the correct in-plane exchange constant of FeCl2 emerges from the series expansion of m(H) involved in the analysis.

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