Formation of midgap states and ferromagnetism in semiconducting CaB 6

B. K. Cho, Jong Soo Rhyee, B. H. Oh, M. H. Jung, H. C. Kim, Y. K. Yoon, Jae Hoon Kim, T. Ekino

Research output: Contribution to journalArticle

Abstract

We present a consistent overall picture of the electronic structure and ferromagnetic interaction in CaB6, based on our joint transport, optical, and tunneling measurements on high-quality defect-controlled single crystals. Pure CaB6 single crystals, synthesized with 99.9999% pure boron, exhibited fully semiconducting characteristics, such as monotonic resistance for 2-300 K, a tunneling conductance gap, and an optical absorption threshold at 1.0 eV. Boron-related defects formed in CaB6 single crystals synthesized with 99.9% pure boron induced midgap states 0.18 eV below the conduction band and extra free charge carriers, with the transport, optical, and tunneling properties substantially modified. Remarkably, no ferromagnetic signals were detected from single crystals made with 99.9999% pure boron, regardless of stoichiometry, whereas those made with 99.9% boron exhibited ferromagnetism within a finite range of carrier density. The possible surmise between the electronic state and magnetization will be discussed.

Original languageEnglish
Article number113202
Pages (from-to)1132021-1132024
Number of pages4
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume69
Issue number11
Publication statusPublished - 2004 Mar 1

Fingerprint

Boron
Ferromagnetism
ferromagnetism
boron
Single crystals
single crystals
Defects
defects
Electronic states
Conduction bands
Charge carriers
optical measurement
Stoichiometry
Light absorption
Electronic structure
Carrier concentration
charge carriers
stoichiometry
Magnetization
conduction bands

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Cho, B. K., Rhyee, J. S., Oh, B. H., Jung, M. H., Kim, H. C., Yoon, Y. K., ... Ekino, T. (2004). Formation of midgap states and ferromagnetism in semiconducting CaB 6. Physical Review B - Condensed Matter and Materials Physics, 69(11), 1132021-1132024. [113202].
Cho, B. K. ; Rhyee, Jong Soo ; Oh, B. H. ; Jung, M. H. ; Kim, H. C. ; Yoon, Y. K. ; Kim, Jae Hoon ; Ekino, T. / Formation of midgap states and ferromagnetism in semiconducting CaB 6. In: Physical Review B - Condensed Matter and Materials Physics. 2004 ; Vol. 69, No. 11. pp. 1132021-1132024.
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Cho, BK, Rhyee, JS, Oh, BH, Jung, MH, Kim, HC, Yoon, YK, Kim, JH & Ekino, T 2004, 'Formation of midgap states and ferromagnetism in semiconducting CaB 6', Physical Review B - Condensed Matter and Materials Physics, vol. 69, no. 11, 113202, pp. 1132021-1132024.

Formation of midgap states and ferromagnetism in semiconducting CaB 6. / Cho, B. K.; Rhyee, Jong Soo; Oh, B. H.; Jung, M. H.; Kim, H. C.; Yoon, Y. K.; Kim, Jae Hoon; Ekino, T.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 69, No. 11, 113202, 01.03.2004, p. 1132021-1132024.

Research output: Contribution to journalArticle

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AB - We present a consistent overall picture of the electronic structure and ferromagnetic interaction in CaB6, based on our joint transport, optical, and tunneling measurements on high-quality defect-controlled single crystals. Pure CaB6 single crystals, synthesized with 99.9999% pure boron, exhibited fully semiconducting characteristics, such as monotonic resistance for 2-300 K, a tunneling conductance gap, and an optical absorption threshold at 1.0 eV. Boron-related defects formed in CaB6 single crystals synthesized with 99.9% pure boron induced midgap states 0.18 eV below the conduction band and extra free charge carriers, with the transport, optical, and tunneling properties substantially modified. Remarkably, no ferromagnetic signals were detected from single crystals made with 99.9999% pure boron, regardless of stoichiometry, whereas those made with 99.9% boron exhibited ferromagnetism within a finite range of carrier density. The possible surmise between the electronic state and magnetization will be discussed.

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Cho BK, Rhyee JS, Oh BH, Jung MH, Kim HC, Yoon YK et al. Formation of midgap states and ferromagnetism in semiconducting CaB 6. Physical Review B - Condensed Matter and Materials Physics. 2004 Mar 1;69(11):1132021-1132024. 113202.