Co2MnX (X=Si, Ge, Sn) Heusler compounds: An ab initio study of their structural, electronic, and magnetic properties at zero and elevated pressure

S. Picozzi, A. Continenza, Arthur J Freeman

Research output: Contribution to journalArticle

461 Citations (Scopus)

Abstract

The structural, electronic, and magnetic properties of Co2MnX (X = Si, Ge, Sn) Heusler compounds have been determined by means of all-electron full-potential linearized augmented plane wave (FLAPW) calculations. We focus on the effects on the electronic and magnetic properties induced by: (i) substitution of the X atom, (ii) applied pressure, and (iii) the use of the local spin density approximation (LSDA) vs the generalized gradient approximation (GGA) in density functional theory. A comparison between LSDA and GGA for the exchange-correlation functional shows that GGA is essential for an accurate description of the equilibrium volumes and of the electronic and magnetic properties of these systems. We find that both the energy gap and the spin gap increase as the X atomic number decreases. As a result of the semiconducting (metallic) character found in the minority (majority) spin band structure, the Si and Ge based alloys are predicted to be halfmetallic. In contrast, Co2MnSn is found to be a "nearly half-metallic" compound, since the minority valence band maximum crosses the Fermi level. The calculated total magnetization of 5 μB is in excellent agreement with recent experiments. By including a fully self-consistent treatment of spin-orbit coupling, the GGA calculated orbital moments are shown to be very small (about 0.008 μB for Mn and about 0.02 μB for Co), showing that the quenching of the orbital magnetic moment is nearly complete. The calculated hyperfine fields, both at zero and elevated pressure, are compared with available experimental data, and show general agreement, except for Mn. Finally, the calculated Mn 2p exchange splittings, found to be in good agreement with experiment, are proportional to the Mn magnetic moments, suggesting a localized nature of ferromagnetism in these Heusler compounds.

Original languageEnglish
Article number094421
Pages (from-to)944211-944219
Number of pages9
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume66
Issue number9
Publication statusPublished - Sep 1 2002

Fingerprint

Electronic properties
Structural properties
Magnetic properties
magnetic properties
Magnetic moments
approximation
electronics
Metallic compounds
gradients
Ferromagnetism
minorities
Valence bands
Fermi level
Band structure
Density functional theory
Quenching
Magnetization
Orbits
Energy gap
Substitution reactions

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

@article{abbb0626e5e94ec5b90d041fe54d09a6,
title = "Co2MnX (X=Si, Ge, Sn) Heusler compounds: An ab initio study of their structural, electronic, and magnetic properties at zero and elevated pressure",
abstract = "The structural, electronic, and magnetic properties of Co2MnX (X = Si, Ge, Sn) Heusler compounds have been determined by means of all-electron full-potential linearized augmented plane wave (FLAPW) calculations. We focus on the effects on the electronic and magnetic properties induced by: (i) substitution of the X atom, (ii) applied pressure, and (iii) the use of the local spin density approximation (LSDA) vs the generalized gradient approximation (GGA) in density functional theory. A comparison between LSDA and GGA for the exchange-correlation functional shows that GGA is essential for an accurate description of the equilibrium volumes and of the electronic and magnetic properties of these systems. We find that both the energy gap and the spin gap increase as the X atomic number decreases. As a result of the semiconducting (metallic) character found in the minority (majority) spin band structure, the Si and Ge based alloys are predicted to be halfmetallic. In contrast, Co2MnSn is found to be a {"}nearly half-metallic{"} compound, since the minority valence band maximum crosses the Fermi level. The calculated total magnetization of 5 μB is in excellent agreement with recent experiments. By including a fully self-consistent treatment of spin-orbit coupling, the GGA calculated orbital moments are shown to be very small (about 0.008 μB for Mn and about 0.02 μB for Co), showing that the quenching of the orbital magnetic moment is nearly complete. The calculated hyperfine fields, both at zero and elevated pressure, are compared with available experimental data, and show general agreement, except for Mn. Finally, the calculated Mn 2p exchange splittings, found to be in good agreement with experiment, are proportional to the Mn magnetic moments, suggesting a localized nature of ferromagnetism in these Heusler compounds.",
author = "S. Picozzi and A. Continenza and Freeman, {Arthur J}",
year = "2002",
month = "9",
day = "1",
language = "English",
volume = "66",
pages = "944211--944219",
journal = "Physical Review B-Condensed Matter",
issn = "1098-0121",
publisher = "American Physical Society",
number = "9",

}

TY - JOUR

T1 - Co2MnX (X=Si, Ge, Sn) Heusler compounds

T2 - An ab initio study of their structural, electronic, and magnetic properties at zero and elevated pressure

AU - Picozzi, S.

AU - Continenza, A.

AU - Freeman, Arthur J

PY - 2002/9/1

Y1 - 2002/9/1

N2 - The structural, electronic, and magnetic properties of Co2MnX (X = Si, Ge, Sn) Heusler compounds have been determined by means of all-electron full-potential linearized augmented plane wave (FLAPW) calculations. We focus on the effects on the electronic and magnetic properties induced by: (i) substitution of the X atom, (ii) applied pressure, and (iii) the use of the local spin density approximation (LSDA) vs the generalized gradient approximation (GGA) in density functional theory. A comparison between LSDA and GGA for the exchange-correlation functional shows that GGA is essential for an accurate description of the equilibrium volumes and of the electronic and magnetic properties of these systems. We find that both the energy gap and the spin gap increase as the X atomic number decreases. As a result of the semiconducting (metallic) character found in the minority (majority) spin band structure, the Si and Ge based alloys are predicted to be halfmetallic. In contrast, Co2MnSn is found to be a "nearly half-metallic" compound, since the minority valence band maximum crosses the Fermi level. The calculated total magnetization of 5 μB is in excellent agreement with recent experiments. By including a fully self-consistent treatment of spin-orbit coupling, the GGA calculated orbital moments are shown to be very small (about 0.008 μB for Mn and about 0.02 μB for Co), showing that the quenching of the orbital magnetic moment is nearly complete. The calculated hyperfine fields, both at zero and elevated pressure, are compared with available experimental data, and show general agreement, except for Mn. Finally, the calculated Mn 2p exchange splittings, found to be in good agreement with experiment, are proportional to the Mn magnetic moments, suggesting a localized nature of ferromagnetism in these Heusler compounds.

AB - The structural, electronic, and magnetic properties of Co2MnX (X = Si, Ge, Sn) Heusler compounds have been determined by means of all-electron full-potential linearized augmented plane wave (FLAPW) calculations. We focus on the effects on the electronic and magnetic properties induced by: (i) substitution of the X atom, (ii) applied pressure, and (iii) the use of the local spin density approximation (LSDA) vs the generalized gradient approximation (GGA) in density functional theory. A comparison between LSDA and GGA for the exchange-correlation functional shows that GGA is essential for an accurate description of the equilibrium volumes and of the electronic and magnetic properties of these systems. We find that both the energy gap and the spin gap increase as the X atomic number decreases. As a result of the semiconducting (metallic) character found in the minority (majority) spin band structure, the Si and Ge based alloys are predicted to be halfmetallic. In contrast, Co2MnSn is found to be a "nearly half-metallic" compound, since the minority valence band maximum crosses the Fermi level. The calculated total magnetization of 5 μB is in excellent agreement with recent experiments. By including a fully self-consistent treatment of spin-orbit coupling, the GGA calculated orbital moments are shown to be very small (about 0.008 μB for Mn and about 0.02 μB for Co), showing that the quenching of the orbital magnetic moment is nearly complete. The calculated hyperfine fields, both at zero and elevated pressure, are compared with available experimental data, and show general agreement, except for Mn. Finally, the calculated Mn 2p exchange splittings, found to be in good agreement with experiment, are proportional to the Mn magnetic moments, suggesting a localized nature of ferromagnetism in these Heusler compounds.

UR - http://www.scopus.com/inward/record.url?scp=0036752561&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0036752561&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:0036752561

VL - 66

SP - 944211

EP - 944219

JO - Physical Review B-Condensed Matter

JF - Physical Review B-Condensed Matter

SN - 1098-0121

IS - 9

M1 - 094421

ER -