11 / 27
allied
academies
Mater Sci Nanotechnol 2017
Volume 1 Issue 3
Magnetic Materials 2017
Page 83
October 09-10, 2017 London, UK
International Conference on
Spin-Filtering in superconducting junction
with the manganite interlayer
Gennady A Ovsyannikov
Kotel’nikov Institute of Radio Engineering and Electronics RAS, Russia
T
he tunnel current flowing through the ferromagnetic
layer between two non-magnetic electrodes becomes
spin-polarized due to exchange splitting of the ferromagnetic
insulator conduction band with the states with the spin up and
spin down. Electronic and spin transport in superconducting
mesa-structures made of epitaxial cuprate superconductor
YBa
2
Cu
3
Ox(YBCO) and niobium thin films with an
insulating manganite LaMnO
3
(LMO) thin film as interlayer
were investigated. Ferromagnetic resonance measurements of
heterostructure Au/LMO/YBCO shows ferromagnetic state
at temperatures below 150 K, as in the case of reference LMO
film grown on the neodymium gallate substrate. Spin current
in the mesa structure was studied. The heights of the tunneling
barrier in mesa structure Au/LMO/YBCO evaluated from
resistive characteristics of mesa-structures at different
thickness of interlayer showed an exponential decrease
approximately from 30 mV down to 5 mV with increase of
manganite interlayer thickness. Temperature dependence of
the conductivity of mesa-structures could be described taking
into account d-wave superconductivity in YBCO and a spin
filtering of the electron transport. Spin filtering is supported
also by measurements of magneto-resistance and the high
sensitivity of mesa-structure conductivity to weak magnetic
fields. Varying the external weak magnetic field |H|<10 Oe
and dc bias current the microwave generation with a line-
width of order 50 MHz was observed in GHz frequency
band using low noise microwave amplifier. The frequency
of generation could be tuned by biasing current with a rate
10
13
Hz/A. The impact of spin filtering on charge current and
manipulation of spin-dependent switching from oscillating to
non-oscillating states are discussed taking into account the
asymmetry of oscillation amplitudes over applied H-field.
gena@hitech.cplire.ruMaterials Science and Nanotechnology