High-temperature ferromagnetism in CaB2C2

Jun Akimitsu, K. Takenawa, K. Suzuki, H. Harima, Y. Kuramoto

Research output: Contribution to journalArticle

48 Citations (Scopus)

Abstract

We report a high Curie-temperature ferromagnet, CaB2C2. Although the compound has neither transition metal nor rare earth ions, the ferromagnetic transition temperature Tc is about 770 Kelvin. Despite this high Tc, the magnitude of the ordered moment at room temperatures is on the order of 10-4 Bohr magneton per formula unit. These properties are rather similar to those of doped divalent hexaborides, such as Ca1-xLaxB6. The calculated electronic states also show similarity near the Fermi level between CaB2C2 and divalent hexaborides. However, there is an important difference: CaB2C2 crystallizes in a tetragonal structure, and there are no equivalent pockets in the energy bands for electrons and holes - in contrast with CaB6. Thus, the disputed threefold degeneracy, specific to the cubic structure, in the energy bands of divalent hexaborides turns out not to be essential for high-temperature ferromagnetism. It is the peculiar molecular orbitals near the Fermi level that appear to be crucial to the high-Tc ferromagnetism.

Original languageEnglish
Pages (from-to)1125-1127
Number of pages3
JournalScience
Volume293
Issue number5532
DOIs
Publication statusPublished - Aug 10 2001
Externally publishedYes

Fingerprint

Temperature
Rare Earth Metals
Magnets
Transition Temperature
Electrons
Ions

ASJC Scopus subject areas

  • General

Cite this

Akimitsu, J., Takenawa, K., Suzuki, K., Harima, H., & Kuramoto, Y. (2001). High-temperature ferromagnetism in CaB2C2 . Science, 293(5532), 1125-1127. https://doi.org/10.1126/science.1061501

High-temperature ferromagnetism in CaB2C2 . / Akimitsu, Jun; Takenawa, K.; Suzuki, K.; Harima, H.; Kuramoto, Y.

In: Science, Vol. 293, No. 5532, 10.08.2001, p. 1125-1127.

Research output: Contribution to journalArticle

Akimitsu, J, Takenawa, K, Suzuki, K, Harima, H & Kuramoto, Y 2001, 'High-temperature ferromagnetism in CaB2C2 ', Science, vol. 293, no. 5532, pp. 1125-1127. https://doi.org/10.1126/science.1061501
Akimitsu J, Takenawa K, Suzuki K, Harima H, Kuramoto Y. High-temperature ferromagnetism in CaB2C2 . Science. 2001 Aug 10;293(5532):1125-1127. https://doi.org/10.1126/science.1061501
Akimitsu, Jun ; Takenawa, K. ; Suzuki, K. ; Harima, H. ; Kuramoto, Y. / High-temperature ferromagnetism in CaB2C2 . In: Science. 2001 ; Vol. 293, No. 5532. pp. 1125-1127.
@article{5ad89f4f634d441394a4f28a7a4f7ea7,
title = "High-temperature ferromagnetism in CaB2C2",
abstract = "We report a high Curie-temperature ferromagnet, CaB2C2. Although the compound has neither transition metal nor rare earth ions, the ferromagnetic transition temperature Tc is about 770 Kelvin. Despite this high Tc, the magnitude of the ordered moment at room temperatures is on the order of 10-4 Bohr magneton per formula unit. These properties are rather similar to those of doped divalent hexaborides, such as Ca1-xLaxB6. The calculated electronic states also show similarity near the Fermi level between CaB2C2 and divalent hexaborides. However, there is an important difference: CaB2C2 crystallizes in a tetragonal structure, and there are no equivalent pockets in the energy bands for electrons and holes - in contrast with CaB6. Thus, the disputed threefold degeneracy, specific to the cubic structure, in the energy bands of divalent hexaborides turns out not to be essential for high-temperature ferromagnetism. It is the peculiar molecular orbitals near the Fermi level that appear to be crucial to the high-Tc ferromagnetism.",
author = "Jun Akimitsu and K. Takenawa and K. Suzuki and H. Harima and Y. Kuramoto",
year = "2001",
month = "8",
day = "10",
doi = "10.1126/science.1061501",
language = "English",
volume = "293",
pages = "1125--1127",
journal = "Science",
issn = "0036-8075",
publisher = "American Association for the Advancement of Science",
number = "5532",

}

TY - JOUR

T1 - High-temperature ferromagnetism in CaB2C2

AU - Akimitsu, Jun

AU - Takenawa, K.

AU - Suzuki, K.

AU - Harima, H.

AU - Kuramoto, Y.

PY - 2001/8/10

Y1 - 2001/8/10

N2 - We report a high Curie-temperature ferromagnet, CaB2C2. Although the compound has neither transition metal nor rare earth ions, the ferromagnetic transition temperature Tc is about 770 Kelvin. Despite this high Tc, the magnitude of the ordered moment at room temperatures is on the order of 10-4 Bohr magneton per formula unit. These properties are rather similar to those of doped divalent hexaborides, such as Ca1-xLaxB6. The calculated electronic states also show similarity near the Fermi level between CaB2C2 and divalent hexaborides. However, there is an important difference: CaB2C2 crystallizes in a tetragonal structure, and there are no equivalent pockets in the energy bands for electrons and holes - in contrast with CaB6. Thus, the disputed threefold degeneracy, specific to the cubic structure, in the energy bands of divalent hexaborides turns out not to be essential for high-temperature ferromagnetism. It is the peculiar molecular orbitals near the Fermi level that appear to be crucial to the high-Tc ferromagnetism.

AB - We report a high Curie-temperature ferromagnet, CaB2C2. Although the compound has neither transition metal nor rare earth ions, the ferromagnetic transition temperature Tc is about 770 Kelvin. Despite this high Tc, the magnitude of the ordered moment at room temperatures is on the order of 10-4 Bohr magneton per formula unit. These properties are rather similar to those of doped divalent hexaborides, such as Ca1-xLaxB6. The calculated electronic states also show similarity near the Fermi level between CaB2C2 and divalent hexaborides. However, there is an important difference: CaB2C2 crystallizes in a tetragonal structure, and there are no equivalent pockets in the energy bands for electrons and holes - in contrast with CaB6. Thus, the disputed threefold degeneracy, specific to the cubic structure, in the energy bands of divalent hexaborides turns out not to be essential for high-temperature ferromagnetism. It is the peculiar molecular orbitals near the Fermi level that appear to be crucial to the high-Tc ferromagnetism.

UR - http://www.scopus.com/inward/record.url?scp=0035839137&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0035839137&partnerID=8YFLogxK

U2 - 10.1126/science.1061501

DO - 10.1126/science.1061501

M3 - Article

VL - 293

SP - 1125

EP - 1127

JO - Science

JF - Science

SN - 0036-8075

IS - 5532

ER -