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Resolving anomalies in the critical exponents of FePt using finite-size scaling in magnetic fields

Resolving anomalies in the critical exponents of FePt using finite-size scaling in magnetic fields
Resolving anomalies in the critical exponents of FePt using finite-size scaling in magnetic fields
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.
HAMR, Finite-size scaling, Critical Exponents
Waters, Jonathon, Michael
654aacd1-a303-48a3-bcfe-4de10af2e34d
Kramer, Denis
1faae37a-fab7-4edd-99ee-ae4c30d3cde4
Sluckin, T.J.
8dbb6b08-7034-4ae2-aa65-6b80072202f6
Hovorka, Ondrej
a12bd550-ad45-4963-aa26-dd81dd1609ee
Waters, Jonathon, Michael
654aacd1-a303-48a3-bcfe-4de10af2e34d
Kramer, Denis
1faae37a-fab7-4edd-99ee-ae4c30d3cde4
Sluckin, T.J.
8dbb6b08-7034-4ae2-aa65-6b80072202f6
Hovorka, Ondrej
a12bd550-ad45-4963-aa26-dd81dd1609ee

Waters, Jonathon, Michael, Kramer, Denis, Sluckin, T.J. and Hovorka, Ondrej (2019) Resolving anomalies in the critical exponents of FePt using finite-size scaling in magnetic fields. Physical Review Applied, 11 (2), [024028]. (doi:10.1103/PhysRevApplied.11.024028).

Record type: Article

Abstract

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.

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Accepted/In Press date: 15 January 2019
e-pub ahead of print date: 11 February 2019
Keywords: HAMR, Finite-size scaling, Critical Exponents

Identifiers

Local EPrints ID: 428277
URI: http://eprints.soton.ac.uk/id/eprint/428277
PURE UUID: bc49b318-eda2-4dd2-b0c7-46ec846b0612
ORCID for T.J. Sluckin: ORCID iD orcid.org/0000-0002-9163-0061
ORCID for Ondrej Hovorka: ORCID iD orcid.org/0000-0002-6707-4325

Catalogue record

Date deposited: 20 Feb 2019 17:30
Last modified: 30 Jan 2020 05:04

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