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Polaronic charge transfer and large dielectric constant in Ca 3 CoRhO 6
Author(s) -
Banerjee A.,
Sannigrahi J.,
Giri S.,
Majumdar S.
Publication year - 2016
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201600178
Subject(s) - condensed matter physics , dielectric , variable range hopping , polaron , activation energy , permittivity , relaxation (psychology) , electrical resistivity and conductivity , materials science , charge carrier , thermal conduction , chemistry , physics , electron , psychology , social psychology , optoelectronics , organic chemistry , quantum mechanics , composite material
We report the dc electrical conductivity and ac impedance study of the spin chain compound Ca3 CoRhO6 . The sample shows a variable range hopping‐assisted dc conduction below 250 K, while a nearest neighbor small polaron hopping is observed at higher temperatures. A reasonably large frequency‐independent ac dielectric permittivity ( ∼ 3200) is observed around room temperature. The activation energy associated with the relaxation peaks in loss tangent below 200 K is found to be close to the variable range hopping energy of the dc resistivity data which signifies the active role of the charge carrier hopping toward the ac dielectric data. The characteristic time constant associated with the relaxation (7.2 × 10 −11 s) and the value of activation energy (116 meV) suggest a polaronic charge transfer in the system. The modulus analysis suggests that the relaxation in permittivity is due to the intrinsic grain effect and it is likely to be associated with charge transfer between transition metal ions in a system where their mixed valence nature is already reported. The sample also shows dielectric anomaly close to the low‐temperature magnetic transition, although we failed to observe any ground state spontaneous electric polarization.