Investigation of the magnetoresistance in EuS/Nb:SrTiO3 junction
Jia Lu(芦佳)1, Yu-Lin Gan(甘渝林)1, Yun-Lin Lei(雷蕴麟)2, Lei Yan(颜雷)1, †, and Hong Ding(丁洪)1,3,4$
1 Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences (CAS), Beijing 100190, China 2 College of Physics and Materials Science, Tianjin Normal University, Tianjin 300387, China 3 Department of Physics, University of Chinese Academy of Sciences, Beijing 100049, China 4 CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100049, China
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.
Received: 21 July 2020
Revised: 10 September 2020
Accepted manuscript online: 28 September 2020
Fund: 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).
Jia Lu(芦佳), Yu-Lin Gan(甘渝林), Yun-Lin Lei(雷蕴麟), Lei Yan(颜雷), and Hong Ding(丁洪)$ Investigation of the magnetoresistance in EuS/Nb:SrTiO3 junction 2020 Chin. Phys. B 29 117503
Fig. 1.
(a) The cross-section structure of the EuS/Nb:STO junction; (b) the typical XRD pattern of EuS thin film grown on Nb:STO (100) substrate.
Fig. 2.
(a) The in-plane magnetization hysteresis loops of the EuS (10 nm)/Nb:STO junction measured at 2 K; (b) temperature dependences of the normalized magnetization of epitaxial EuS films grown on Nb:STO and STO substrates, respectively, recorded for magnetic field 3-mT applied parallel to the film surface.
Fig. 3.
(a) I–V characteristics of EuS/Nb:STO in zero magnetic field at various temperature; (b) I–V characteristics of EuS/Nb:STO in various magnetic field at 30 K.
Fig. 4.
(a) The temperature dependence of resistivity of 10-nm EuS/Nb:STO junction measured in various magnetic field, the sharp decrease of R indicates the onset of ferromagnetic transition; (b) magnetoresistance of the EuS/Nb:STO junction as a function of magnetic field at various temperature; the hysteretic behavior displayed at T = 8 K.
Fig. 5.
(a) R–T curve and (b) magnetoresistance (at 30 K) of the junction with EuS barrier of 10 nm, 24 nm, and 45 nm.
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