title: Electron transport and thermoelectric properties of layered perovskite LaBaCo(2)O(5.5).
abstract: We have investigated systematically the physical transport properties of layered 112-type cobaltite by means of electrical resistivity, magnetoresistance and thermopower measurements. In order to understand the complex transport mechanism of LaBaCo(2)O(5.5), the data have been analysed using different theoretical models. The compound shows an electronic transition between two semiconducting states around 326 K, which coincides with the ferromagnetic transition. Interestingly, the system also depicts a significant magnetoresistance (MR) effect near the ferro/antiferromagnetic phase boundary and the highest value of MR is close to 5% at 245 K under ± 7 T. The temperature dependence of thermopower, S(T), exhibits p-type conductivity in the 60 K≤T≤320 K range and reaches a maximum value of around 303 µV K(-1) (at 120 K). In the low temperature antiferromagnetic region the unusual S(T) behaviour, generally observed for the cobaltite series LnBaCo(2)O(5.5) (Ln = rare earth), is explained by the electron magnon scattering mechanism.
authors.affiliation: Laboratoire CRISMAT, ENSICAEN UMR6508, 6 Boulevard Maréchal Juin, F-14050 Caen Cedex 4, France. Solid State Physics Laboratory, Defence Research and Development Organization, Lucknow Road, Timarpur, Delhi 110054, India.
authors.forename: Asish K
authors.initials: AK
authors.lastname: Kundu
authors.forename: B
authors.initials: B
authors.lastname: Raveau
authors.forename: V
authors.initials: V
authors.lastname: Caignaert
authors.forename: E-L
authors.initials: EL
authors.lastname: Rautama
authors.forename: V
authors.initials: V
authors.lastname: Pralong