Spin-dependent magnetoresistance of ferromagnet/superconductor/ferromagnetLa0.7Ca0.3MnO3∕YBa2Cu3

Abstract

We report on large magnetoresistance in ferromagnet/superconductor/ferromagnet trilayer structures made of La 0.7 Ca 0.3 MnO 3 and YBa 2 Cu 3 O 7 . We find that the shape and height of the magnetoresistance peaks are not modified when the relative orientation of current and magnetic field is changed from parallel to perpendicular. Furthermore, we find that the temperature shift of the resistance curves is independent of current and of the sweep rate of the magnetic field. These observations favor the view that the magnetoresistance phenomenon originates in the spin dependent transport of quasiparticles transmitted from the ferromagnetic electrodes into the superconductor, and rule out interpretations in terms of spontaneous vortices or anisotropic magnetoresistance of the ferromagnetic layers.

Spin-polarized current versus stray field in a perpendicularly magnetized superconducting spin switch

“…4 In a FSF spin switch, the transition temperature T c of an S layer sandwiched between two F layers depends on their relative inplane magnetization orientation-parallel ͑P͒ or antiparallel ͑AP͒-with T c P Ͻ T c AP . 2,3,8 In this case, it is important to confirm that no finite domains generating magnetic stray fields are formed due to interlayer magnetostatic coupling. 7 In order to explain T c P Ͼ T c AP in S/F-ML two conflicting models have been proposed.…”

Reversal magnetoresistance effect in ferromagnet/superconductor/ferromagnet/antiferromagnet heterostructure

“…The dependence of activation energy on the magnetic field is in an inverse power law of U͑H , T͒ ϰ 1 / H 0.5 . 15,20,22 The MR peaks for the system are possibly superimposed on a resistance background which increases with magnetic field. In Fig.…”

“…14 Moreover, the same research group explores different mechanisms as possible origins of the MR in such a system. 15 These investigations show that the MR depends on the relative orientation of the magnetic layers, and is independent of the relative direction of current and field, which rules out vortex dissipation or anisotropic MR as the resource of the abovementioned MR phenomenon.…”

Multifunctional La0.7Sr0.3MnO3-YBa2Cu3O7Heterostructures

“…In another nonlocal process electron co-tunneling (EC) in which the electron enters the superconductor through one contact and electron of the same spin leaves through another contact yields a positive resistance. If the two contacts are spin polarized CAR and EC are favorable for antiparallel and parallel alignment of magnetic domains, respectively [7,10,11]. Referring such scenario to our samples it is possible that in our case the role of different contacts is played by magnetic domains, if the domain wall width is not larger than the ξ ab ≈ 3 nm.…”

“…Another possibility for long-range superconducting correlation penetration to a distance much longer than coherence length, ξ F ∼ (hD/2E ex ) 1/2 , is the effect of crossed Andreev reflection (CAR) [5][6][7][8][9] occurring in the vicinity of magnetic domain walls (DW). Recent report [10,11] on LSMO/YBCO/LSMO trilayer structures demonstrate large magnetoresistance at temperatures in vicinity of superconducting transition temperature. In this work we investigate the MR effect in LSMO/YBCO/LSMO trilayer structures.…”