resumo
We have studied the effects of hydrostatic pressure on the electrical transport and magnetic properties of La1.32Sr1.68Mn2O7 layered manganite up to 25 kbars. At ambient pressure, the Compound exhibits a ferromagnetic transition accompanied by a metal-insulator transition (T-MI(1)) at 1.18 K. Increasing pressure induces a second metal-insulator (T-MI(2)) transition at a critical pressure of 6 <= P-C <= 7 kbars in the temperature dependence of resistivity measurement. With further increase in pressure, both T-MI(1) and T-MI(2) shift to higher temperatures continuously, however, displaying a suppression in the amplitude of the peaks on the resistivity curves. We could not observe any transition corresponding to T-MI(2) in the temperature dependence of magnetization measurement under pressures up to 10 Bars. However, pressure reduces the magnetic moments at low temperatures and shifts the T-C to higher temperatures at the same rate observed for T-MI(1). A large negative tunneling magnetoresistance was observed around T-C due to the applied magnetic field up to the maximum available value of 5 T, and the pressure reduces the magnetoresistance ratio significantly. This result is due to the canted ferromagnetic order that was established by increasing pressure, which leads to an electron localized ferromagnetic insulating phase. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3256182]
palavras-chave
INTERPLANE TUNNELING MAGNETORESISTANCE; DOUBLE EXCHANGE; BILAYER MANGANITE; PHASE-SEPARATION; T-C; CRYSTAL; LA1.2SR1.8MN2O7
categoria
Physics
autores
Kumaresavanji, M; Reis, MS; Xing, YT; Fontes, MB
Grupos
agradecimentos
We are grateful to Professor Elisa B. Saitovitch and Professor M. Continentino for their valuable discussion and suggestions. This work is supported by the Edital Universal-CNPq Grant No. 470940/2007-7, APQ1-FAPERJ Grant No. E26/170.717/2007, and Pronex-FAPERJ Grant No. E-26/171.165/2003 M.K. acknowledges the Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq), Brazil and the Third World Academy of Sciences (TWAS), Italy for the award of CNPq-TWAS fellowship.