Colossal magnetoresistance behavior in LaCaMnO/CeO2/Si (100) multilayers grown by pulsed laser deposition (abstract)

Abstract

The La–Ca–Mn–O (LCMO) system grown on lattice matched LaAlO3 substrates by pulsed laser deposition (PLD) has attracted much recent attention because of the colossal magnetoresistance exhibited. Interest in these materials is because of their potential application in the magnetic recording industry where one of the challenges is to integrate the chip signal-conditioning circuits together with the sensing elements. We have previously reported the giant magnetoresistance characteristics of La–Ca–Mn–O films grown on Si (100) substrates by PLD. Although magnetoresistance at 50 K under a field of 4.7 T was more than 35% (Δρ/ρ0), no colossal magnetoresistance values were present, clearly due to the imperfections introduced by the lattice mismatch between film and substrate. In this paper we report the transport properties and colossal magnetoresistance behavior in LCMO/CeO2/Si(100) multilayers grown by PLD. The CeO2 is attractive as a buffer layer due to its lattice constant, a, of 5.411 Å, which is close to that of silicon (the misfit factor, being only 0.35%). And by simply rotating the unit cell 45° in the basal plane, the mismatch is less than 0.16% with LCMO along the a–b plane. It is found that the LCMO/CeO2/ Si(100) multilayers also exhibit a well-defined peak of resistivity versus temperature, a similar behavior to a single LCMO layer on a Si substrate. A magnetoresistance value of more than 93% (Δρ/ρ0) was obtained at 77 K under a field of 12 T. The films have been characterized by vibrating sample magnometer, four-point probe and scaning tunneling microscopy, and details of the influence of the multilayer preparation parameter will also be discussed.