B2 Atomic Disorder in Co2FeXMn1-XSi Heusler Alloys

Philip James Hasnip; C.H. Loach; J.H. Smith; Matthew Ian James Probert; Daniel Gilks; James Sizeland; Kenta Yoshida; Mikihiko Oogane; Atsufumi Hirohata; Vlado Lazarov

doi:10.3379/msjmag.1402R010

B2 Atomic Disorder in Co2FeXMn1-XSi Heusler Alloys

Philip James Hasnip, C.H. Loach, J.H. Smith, Matthew Ian James Probert, Daniel Gilks, James Sizeland, Kenta Yoshida, Mikihiko Oogane, Atsufumi Hirohata, Vlado Lazarov

Research output: Contribution to journal › Article › peer-review

Abstract

Co-based full Heusler alloys have attracted significant attention due to their high spin polarisation and successful integration as electrodes in magnetic tunnelling junctions and current-perpendicular-to-plane spin valves (CPP-SV)._Further improvement of the CFMS based CPP-SVs requires a fundamental understanding of the effects of atomic disorder within the Heusler alloys. In this work we present a theoretical study of disorder in CFMS alloys using ab initio simulations, guided by images from Z-contrast scanning-TEM of sample films. The simulations are based on density functional theory plus a Hubbard U term, allowing the investigation of the effects of atomic disorder on the spin-polarisation at the Fermi level, and computation of the disorder formation energy. It is found that in order to retain the high spin-polarisation at the Fermi level the integrity of the Co-sublattice should be preserved, but that the effect of mixing between the Fe/Mn and Si sublattices (B2 phase) varies dramatically depending on the precise nature of the disorder and the chemical composition of the CFMS. Calculations of the spin-polarisation at the Fermi energy show that Co2Fe0.5Mn0.5Si is especially robust with respect to such intermixing, an observation which may explain the good performance of films in this composition range.

Original language	English
Pages (from-to)	50-55
Number of pages	5
Journal	Journal of the Magnetics Society of Japan
Volume	38
Issue number	2-2
DOIs	https://doi.org/10.3379/msjmag.1402R010
Publication status	Published - 2014

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10.3379/msjmag.1402R010

Cite this

@article{5d9ef050a1844bf98e5baeb7ae79d708,

title = "B2 Atomic Disorder in Co2FeXMn1-XSi Heusler Alloys",

abstract = "Co-based full Heusler alloys have attracted significant attention due to their high spin polarisation and successful integration as electrodes in magnetic tunnelling junctions and current-perpendicular-to-plane spin valves (CPP-SV)._Further improvement of the CFMS based CPP-SVs requires a fundamental understanding of the effects of atomic disorder within the Heusler alloys. In this work we present a theoretical study of disorder in CFMS alloys using ab initio simulations, guided by images from Z-contrast scanning-TEM of sample films. The simulations are based on density functional theory plus a Hubbard U term, allowing the investigation of the effects of atomic disorder on the spin-polarisation at the Fermi level, and computation of the disorder formation energy. It is found that in order to retain the high spin-polarisation at the Fermi level the integrity of the Co-sublattice should be preserved, but that the effect of mixing between the Fe/Mn and Si sublattices (B2 phase) varies dramatically depending on the precise nature of the disorder and the chemical composition of the CFMS. Calculations of the spin-polarisation at the Fermi energy show that Co2Fe0.5Mn0.5Si is especially robust with respect to such intermixing, an observation which may explain the good performance of films in this composition range.",

author = "Hasnip, {Philip James} and C.H. Loach and J.H. Smith and Probert, {Matthew Ian James} and Daniel Gilks and James Sizeland and Kenta Yoshida and Mikihiko Oogane and Atsufumi Hirohata and Vlado Lazarov",

year = "2014",

doi = "10.3379/msjmag.1402R010",

language = "English",

volume = "38",

pages = "50--55",

journal = "Journal of the Magnetics Society of Japan",

issn = "0285-0192",

number = "2-2",

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TY - JOUR

T1 - B2 Atomic Disorder in Co2FeXMn1-XSi Heusler Alloys

AU - Hasnip, Philip James

AU - Loach, C.H.

AU - Smith, J.H.

AU - Probert, Matthew Ian James

AU - Gilks, Daniel

AU - Sizeland, James

AU - Yoshida, Kenta

AU - Oogane, Mikihiko

AU - Hirohata, Atsufumi

AU - Lazarov, Vlado

PY - 2014

Y1 - 2014

N2 - Co-based full Heusler alloys have attracted significant attention due to their high spin polarisation and successful integration as electrodes in magnetic tunnelling junctions and current-perpendicular-to-plane spin valves (CPP-SV)._Further improvement of the CFMS based CPP-SVs requires a fundamental understanding of the effects of atomic disorder within the Heusler alloys. In this work we present a theoretical study of disorder in CFMS alloys using ab initio simulations, guided by images from Z-contrast scanning-TEM of sample films. The simulations are based on density functional theory plus a Hubbard U term, allowing the investigation of the effects of atomic disorder on the spin-polarisation at the Fermi level, and computation of the disorder formation energy. It is found that in order to retain the high spin-polarisation at the Fermi level the integrity of the Co-sublattice should be preserved, but that the effect of mixing between the Fe/Mn and Si sublattices (B2 phase) varies dramatically depending on the precise nature of the disorder and the chemical composition of the CFMS. Calculations of the spin-polarisation at the Fermi energy show that Co2Fe0.5Mn0.5Si is especially robust with respect to such intermixing, an observation which may explain the good performance of films in this composition range.

AB - Co-based full Heusler alloys have attracted significant attention due to their high spin polarisation and successful integration as electrodes in magnetic tunnelling junctions and current-perpendicular-to-plane spin valves (CPP-SV)._Further improvement of the CFMS based CPP-SVs requires a fundamental understanding of the effects of atomic disorder within the Heusler alloys. In this work we present a theoretical study of disorder in CFMS alloys using ab initio simulations, guided by images from Z-contrast scanning-TEM of sample films. The simulations are based on density functional theory plus a Hubbard U term, allowing the investigation of the effects of atomic disorder on the spin-polarisation at the Fermi level, and computation of the disorder formation energy. It is found that in order to retain the high spin-polarisation at the Fermi level the integrity of the Co-sublattice should be preserved, but that the effect of mixing between the Fe/Mn and Si sublattices (B2 phase) varies dramatically depending on the precise nature of the disorder and the chemical composition of the CFMS. Calculations of the spin-polarisation at the Fermi energy show that Co2Fe0.5Mn0.5Si is especially robust with respect to such intermixing, an observation which may explain the good performance of films in this composition range.

U2 - 10.3379/msjmag.1402R010

DO - 10.3379/msjmag.1402R010

M3 - Article

SN - 0285-0192

VL - 38

SP - 50

EP - 55

JO - Journal of the Magnetics Society of Japan

JF - Journal of the Magnetics Society of Japan

IS - 2-2

ER -