Title: Resolving anomalies in the critical exponents of FePt using finite-size scaling in magnetic fields
Authors: Waters, Jonathon Michael
Kramer, Denis 
Sluckin, T.J.
Hovorka, Ondrej
Language: en
Keywords: HAMR;Finite-size scaling;Critical Exponents
Subject (DDC): DDC::500 Naturwissenschaften und Mathematik::530 Physik::538 Magnetismus
Issue Date: 2019
Publisher: American Physical Society
Document Type: Article
Journal / Series / Working Paper (HSU): Physical Review Applied 
Volume: 11
Issue: 2
Publisher Place: College Park, Md. [u.a.]
FePt is the primary material being considered for the development of information storage technologies based on heat-assisted magnetic recording (HAMR). A practical realization of HAMR requires understanding the high-temperature phase transition behavior of FePt, including critical exponents and Curie temperature distributions as the fundamental HAMR media design characteristics. The studies so far found a significant degree of variability in the values of critical exponents of FePt and remain controversial. Here, we show that at the heart of this variability is the phase transition crossover phenomenon induced by two-ion anisotropy of FePt. Through Monte Carlo simulations based on a realistic FePt effective Hamiltonian, we demonstrate that in order to identify the critical exponents accurately, it is necessary to base the analysis on field-dependent magnetization data. We have developed a two-variable finite-size scaling method that accounts for the field effect. Through the use of this method, we show unambiguously that true critical exponents of FePt are fully consistent with the three-dimensional Heisenberg universality class.
Organization Units (connected with the publication): Engineering and Physical Sciences, University of Southampton, Southampton, SO17 1BJ, United Kingdom
ISSN: 2331-7019
DOI: 10.1103/PhysRevApplied.11.024028
Appears in Collections:Publications of the HSU Researchers (before HSU)

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