Investigation of the magnetoresistance in EuS/Nb:SrTiO3 junction* *Project supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant Nos. XDB28000000 and XDB07000000), the National Key Research and Development Program of China (Grant No. 2016YFA0300600), and the Fund from the Beijing Municipal Science & Technology Commission (Grant No. Z191100007219012).

Abstract

EuS is one of typical ferromagnetic semiconductor using as spin filter in spintronic devices, and the doped one could be a good spin injector. Herein, we fabricate a spin-functional tunnel junction by epitaxially growing the ferromagnetic EuS film on Nb-doped SrTiO3. The improvement of Curie temperature up to 35 K is associated with indirect exchange through additional charge carriers at the interface of EuS/Nb:STO junction. Its magnetic field controlled current–voltage curves indicate the large magnetoresistance (MR) effect in EuS barriers as a highly spin-polarized injector. The negative MR is up to 60% in 10-nm EuS/Nb:STO at 4 T and 30 K. The MR is enhanced with increasing thickness of EuS barrier. The large negative MR effect over a wide temperature range makes this junction into a potential candidate for spintronic devices.