Structure and transport properties of La.sub.1-x./sub.Sr.sub.x./sub.MnO.sub.3./sub. granular ceramics

0473951 - FZÚ 2018 RIV GB eng J - Článek v odborném periodiku
Jirák, Zdeněk - Hirschner, Jan - Kaman, Ondřej - Knížek, Karel - Levinský, Petr - Maryško, Miroslav - Hejtmánek, Jiří
Structure and transport properties of La_1-xSr_xMnO₃ granular ceramics.
Journal of Physics D-Applied Physics. Roč. 50, č. 7 (2017), 1-15, č. článku 075001. ISSN 0022-3727. E-ISSN 1361-6463
Grant CEP: GA ČR GA15-10088S
Institucionální podpora: RVO:68378271
Klíčová slova: magnetic nanoparticles * perovskite manganite * tunnelling magnetoresistance
Obor OECD: Condensed matter physics (including formerly solid state physics, supercond.)
Impakt faktor: 2.373, rok: 2017

Two granular ceramics were prepared by spark plasma sintering (SPS) at 600–800 ˚C and classical ceramic sintering (CCS) at 900 ˚C using molten salt synthesized nanoparticles of the composition La0.53Sr0.47MnO3 and ≈ 40 nm size. Both the SPS and CCS products essentially retain the two-phase magnetic structure of the starting nanoparticles, which consist of a ferromagnetic FM core and an A-type AFM shell. After the sintering, the AFM phase forms a 10–15 nm thick spacer between neighbouring FM granules. This assembly retains reasonable conductivity down to the lowest temperatures, and it still gives rise to a large negative magnetoresistance. In a detailed analysis of the low-field magnetoconductance and high-field magnetoconductance effects, which are related to the field-induced alignment of the FM granules and spin canting in the AFM matrix, respectively, we conclude that the bulk conductivity is governed by resonant tunnelling.
Trvalý link: http://hdl.handle.net/11104/0271049