Finite-size scaling in thin Fe/Ir(100) layers

TL;DR

This study investigates the finite-size scaling behavior of critical temperatures in thin Fe layers on Ir(100) using Mössbauer spectroscopy, revealing an effective shift exponent consistent with 3D Heisenberg universality after correction considerations.

Contribution

The paper introduces a phenomenological finite-size scaling analysis that accounts for corrections, aligning experimental results with theoretical predictions for the universality class.

Findings

Effective shift exponent lambda ≈ 3.15 before corrections

Corrected lambda ≈ 3.0 consistent with 3D Heisenberg class

Earlier CoO film data are also explained

Abstract

The critical temperature of thin Fe layers on Ir(100) is measured through M\"o{\ss}bauer spectroscopy as a function of the layer thickness. From a phenomenological finite-size scaling analysis, we find an effective shift exponent lambda = 3.15 +/- 0.15, which is twice as large as the value expected from the conventional finite-size scaling prediction lambda=1/nu, where nu is the correlation length critical exponent. Taking corrections to finite-size scaling into account, we derive the effective shift exponent lambda=(1+2\Delta_1)/nu, where Delta_1 describes the leading corrections to scaling. For the 3D Heisenberg universality class, this leads to lambda = 3.0 +/- 0.1, in agreement with the experimental data. Earlier data by Ambrose and Chien on the effective shift exponent in CoO films are also explained.