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Title: A family of rare earth molybdenum bronzes: Oxides consisting of periodic arrays of interacting magnetic units

The family of rare earth molybdenum bronzes, reduced ternary molybdates of composition LnMo16O44, was synthesized and a detailed structural study carried out. Bond valence sum (BVS) calculations clearly show that the molybdenum ions in tetrahedral coordination are hexavalent while the electron count in the primitive unit cell is odd. Yet, measurements show that the phases are semiconductors. The temperature dependence of the magnetic susceptibility of samples containing several different rare earth elements was measured. These measurements verified the presence of a 6.5 K magnetic phase transition not arising from the rare earth constituent, but likely associated with the unique isolated ReO3-type Mo8O36 structural subunits in this phase. To better understand the behavior of these materials, electronic structure calculations were performed within density functional theory. Results suggest a magnetic state in which these structural moieties have an internal ferromagnetic arrangement, with small ~1/8 μB moments on each Mo. We suggest that the Mo8O36 units behave like pseudoatoms with spin ½ derived from a single hole distributed over the eight Mo atoms that are strongly hybridized with the O atoms of the subunit. As a result, while the compound is antiferromagnetic, our calculations suggest that a field-stabilized ferromagnetic state, if achievable, willmore » be a narrow band half-metal.« less
Authors:
 [1] ;  [2] ;  [3] ;  [2] ;  [4] ;  [5]
  1. Montclair State Univ., Montclair, NJ (United States)
  2. FAMU-FSU College of Engineering, Tallahassee, FL (United States); National High Magnetic Field Lab., Tallahassee, FL (United States)
  3. National High Magnetic Field Lab., Tallahassee, FL (United States)
  4. FAMU-FSU College of Engineering, Tallahassee, FL (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
OSTI Identifier:
1333511
Grant/Contract Number:
SC0008832
Type:
Accepted Manuscript
Journal Name:
Journal of Solid State Chemistry
Additional Journal Information:
Journal Volume: 227; Journal Issue: C; Journal ID: ISSN 0022-4596
Publisher:
Elsevier
Research Org:
Florida State Univ., Tallahassee, FL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Contributing Orgs:
Oak Ridge National Laboratory; Montclair State University
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE molybdenum bronzes; crystallographic structure; magnetism; Mo8O36 units; DFT calculations