Abstract
Magnetic tunnel junctions composed of the colossal magnetoresistance material La 0.7 Sr 0.3 Mn O 3 (LSMO) and magnetite ( Fe 3 O 4 ) have been fabricated and characterized. The films were grown on (110) Sr Ti O 3 substrates using pulsed laser deposition, with the nonmagnetic spinel Mg 2 Ti O 4 (MTO) chosen as the barrier layer in order to provide a well lattice-matched isostructural interface with the Fe 3 O 4 electrode. Junction magnetoresistance (JMR) values of up to − 26 % were observed for junctions with 50 - Å -thick MTO barriers at 70 K . Measurements were performed on junctions with barrier thicknesses ranging from 50 - 120 Å . The resistance jumps in JMR correspond well to the switching fields of the LSMO and Fe 3 O 4 magnetic electrodes. The magnitude of the JMR peaks and then begins to decline with decreasing temperature, indicating that prior observations of such temperature-dependent JMR behavior in Co Cr 2 O 4 barrier junctions were due to the electrode at low temperatures rather than to magnetic moments in the Co Cr 2 O 4 .