Triplet superconducting correlations in oxide heterostructures with a composite ferromagnetic interlayer

Superconducting mesa-structures with a spin filtering manganite interlayer

“…According to results [13,14], the LMO manganite of stoichiometric composition has the properties of an insulator and is an antiferromagnet at low temperatures. But a small change in the oxygen content leads to the appearance of ferromagnetism with the Curie temperature of order 140-150 K. A ferromagnetism for the LMO films was reported in [15] and confirmed by measurements of temperature dependence of ferromagnetic resonance magnetic field H 0 (T) [16]. Fig.2 shows temperature dependences ρ(T) of resistivity of LMO film and the ferromagnetic resonance dependence.…”

“…The observed value of magnetoresistance of mesa-structure is typical for manganites [12] and took place only at temperatures below the critical temperature of bilayer Au-Nb. With an increase of dc bias voltage above 3 mV (about twice higher than the niobium energy gap), the conductivity of the mesa-structure no longer depends on magnetic field [16]. The magnetoresistance measured at wider magnetic field sweeping range is shown in Fig.5.…”

Magnetic proximity effect and superconducting triplet correlations at the cuprate superconductor and oxide spin valve interface

“…The noncollinearity of the magnetization vectors of the ferromagnetic films contributes to the generation of superconducting triplet correlations having a nonzero spin projection of superconducting carriers, in the ferromagnetic interlayer. 43,51,52 At T % T c , for a field parallel to the substrate plane, there is a sharp increase in the magnetic moment of the heterostructure ( Fig. 2(a)).…”

“…We used substrates with the dimensions 5 Â 5 mm made of (110)NdGaO 3 (NGO), (001) LaAlO 3 (LAO), and (LaAlO 3 ) 0.3 þ (Sr 2 AlTaO 6 ) 0.7 (LSAT). The magnetization vector of the LSMO epitaxial film deposited on a (110)NGO substrate or onto a (001)YBCO film, is generally in the plane of the substrate, 43,44 whereas for the SRO film the magnetization vector is outside of the plane of the substrates used. 45 A detailed study of the field and temperature dependences of magnetization of the separate films and heterostructures was conducted using a SQUID-magnetometer MPMS-3 produced by Quantum Design in the VSM mode.…”

“…47,48 We investigated mesastructures in which an Au-Nb bilayer served as the top superconducting electrode and was deposited by magnetron sputtering. 43 The use of an epitaxial film made of a cuprate YBCO superconductor as a bottom electrode is made necessary by the need to ensure epitaxial growth of the oxide interlayer, which is composed of two ferromagnetic materials: LSMO with a uniaxial magnetic anisotropy of 20-30 mT and exchange energy of 2.3 meV; 49 and SRO with a magnetic anisotropy of about 1 T and exchange energy of 13 meV. 50 Five square-shaped mesastructures with linear dimensions in the plane L ¼ 10, 20, 30, 40, and 50 lm are prepared on the substrate (hereinafter referred to as "chip") using photolithography techniques, ion beam etching, and explosive photolithography.…”