Effects of pressure on charge transport and magnetic properties of La1.32Sr1.68Mn2O7 layered manganite

Centro Brasileiro de Pesquisas Fisicas, Rua Dr. Xavier Sigaud 150, Urca, 22290-180 Rio de Janeiro, Brazil
Journal of Applied Physics (Impact Factor: 2.21). 12/2009; DOI: 10.1063/1.3256182
Source: IEEE Xplore

ABSTRACT We have studied the effects of hydrostatic pressure on the electrical transport and magnetic properties of La 1.32 Sr 1.68 Mn 2 O 7 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 118 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 kbars. 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 incr-
easing pressure, which leads to an electron localized ferromagnetic insulating phase.

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