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Title: Magnetism and transport properties of layered rare-earth cobaltates Ln{sub 0.3}CoO{sub 2}

The ab-initio (GGA+U) electronic structure calculations of layered cobaltates Ln{sub 0.3}CoO{sub 2} (Ln = La, Pr, Nd) prepared by ionic exchange from Na{sub 0.90}CoO{sub 2} precursors have been performed. The data are used for numerical modeling of Seebeck coefficient within Boltzmann transport theory using BoltzTraP program [G. K. H. Madsen and D. J. Singh, Comput. Phys. Commun. 175, 67 (2006)], as well as for determination of the crystal field split levels of rare-earth ions using a method based on a transformation of Bloch states into the basis of Wannier functions [P. Novák et al., Phys. Rev. B 87, 205139 (2013)]. An overall agreement with observed magnetism and transport properties is obtained. In particular, the high p-type thermopower is well reproduced in a broad temperature range, but instead of theoretical linear decrease down to the lowest temperatures, the real systems exhibit an anomalous change of Seebeck sign, which might be related to the change of bare metallic carriers into the polaronic ones.
Authors:
; ; ; ;  [1] ;  [2]
  1. Institute of Physics ASCR, Cukrovarnická 10, 162 00 Prague 6 (Czech Republic)
  2. Institute of Inorganic Chemistry ASCR, 250 68 Řež near Prague (Czech Republic)
Publication Date:
OSTI Identifier:
22409970
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 17; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; B CODES; COBALT OXIDES; COMPUTERIZED SIMULATION; CRYSTAL FIELD; ELECTRONIC STRUCTURE; LANTHANUM COMPOUNDS; MAGNETISM; NEODYMIUM COMPOUNDS; PRASEODYMIUM COMPOUNDS; PRECURSOR; P-TYPE CONDUCTORS; SODIUM COMPOUNDS; TEMPERATURE DEPENDENCE; TRANSPORT THEORY