resumo
Unusual high temperature ferromagentism is reported for La0.95Sr0.05MnO3 + delta with Curie temperatures (T-C1 and T-C2) T-C1 at 290K and T-C2 similar to 150 K. Weak antiferromagnetism (AFM) is thought to give low moment, low temperature irreversibility, and non-saturation up to 10 T at 5 K. A short-range ferromagnetism is predicted from well-defined hysteresis at 5K and field-cooled (FC) magnetization curves. Strong irreversibility between zero field-cooled (ZFC) and FC at 5 T is due to "hard" spins, not from ferromagnetic clusters. Field-dependent peak shift of spin freezing temperature in ZFC, memory effect, magnetic relaxation shows cluster glass like transition in the system. A metal-insulator transition at 115 K also implies a completion of percolation of short range ferromagnetic clusters, giving an onset of metallic state at 115 K. A complete magnetic phase diagram is presented showing its temperature dependent rich magnetic behavior. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4763460]
palavras-chave
SPIN-GLASSES; LA1-XSRXMNO3; TRANSITION; MAGNETORESISTANCE; ANISOTROPY; TRANSPORT; MAGNETISM; BEHAVIOR; DIAGRAM; OXIDES
categoria
Physics
autores
De, K; Das, S; Roy, A; Dhak, P; Willinger, M; Amaral, JS; Amaral, VS; Giri, S; Majumder, S; Silva, CJR; Gomes, MJM; Mahapatra, PK
nossos autores
João Cunha de Sequeira Amaral
Investigador Auxiliar
Vitor Brás Sequeira Amaral
Professor CatedráticoProjectos
MULTIFOX: Nanometric Probing and Modification of Multiferroic Oxides (PTDC/FIS/105416/2008)
agradecimentos
The authors acknowledge the financial support from UGC-Dr. D. S. Kothari Post-Doctoral Fellowship under the Project No. F.4-2/2006(BSR)/13-307/2008(BSR) (K. De) and from FCT through Grant Numbers SFRH/BPD/47128/2008 (K. De) and SFRH/BD/63698/2009 (A. Roy), from FCT through Grant No. SFRH/BPD/39262/2007 (S. Das), SFRH/BPD/63942/2009 (J. S. Amaral), and partial funding from the program COMPETE-FEDER under Project No. PTDC/FIS/105416/2008. P. Dhak thanks the CSIR, New Delhi for financial support.