Controlling magnetic switching properties of EuS for constructing double spin filter magnetic tunnel junctions

EuS is a well established spin filter (SF) material and its magnetic properties are shown to be tunable with deposition temperature. In tunnel junctions consisting of double EuS SF barriers, different coercive fields of the two adjacent SFs are achieved by depositing one EuS layer at room temperature and quench condensing the other at liquid nitrogen temperature. A thin Al2O3 spacer layer is introduced in between to prevent direct magnetic coupling. Magnetoresistance with well defined spin-parallel and spin-antiparallel states is obtained this way, and the resistance change originates completely within the SF/I/SF composite tunnel barrier, with no ferromagnetic electrodes involved.