Bonding, moment formation, and magnetic interactions in Ca14MnBi11 and Ba14MnBi11

D. Sánchez-Portal, Richard M. Martin, S. M. Kauzlarich, W. E. Pickett

Research output: Contribution to journalArticle

59 Scopus citations

Abstract

"14-1-11" phase compounds, based on magnetic Mn ions and typified by Ca14MnBi11 and Ba14MnBi11, show an unusual magnetic behavior, but the large number (104) of atoms in the primitive cell has precluded any previous full electronic structure study. Using an efficient, local-orbital-based method within the local-spin-density approximation to study the electronic structure, we find a gap between a bonding valence-band complex and an antibonding conduction-band continuum. The bonding bands lack one electron per formula unit of being filled, making them low carrier density p-type metals. The hole resides in the MnBi4 tetrahedral unit, and partially compensates for the high-spin d5 Mn moment, leaving a net spin near 4μB that is consistent with experiment. These manganites are composed of two disjoint but interpenetrating "jungle gym" networks of spin-4/2 MnBi4 9- units with ferromagnetic interactions within the same network, and weaker couplings between the networks whose sign and magnitude is sensitive to materials parameters. Ca14MnBi11 is calculated to be ferromagnetic as observed, while for Ba14MnBi11 (which is antiferromagnetic) the ferromagnetic and antiferromagnetic states are calculated to be essentially degenerate. The band structure of the ferromagnetic states is very close to half metallic.

Original languageEnglish (US)
Article number144414
Pages (from-to)1444141-14441415
Number of pages12997275
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume65
Issue number14
StatePublished - Apr 1 2002
Externally publishedYes

ASJC Scopus subject areas

  • Condensed Matter Physics

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