Temperature dependence of the resistance in applied fields up to 8 T, (YBCO/LSMO/YBCO structures). Note the onset temperature of the electronic inhomogeneity, . The abrupt drop in at is a consistent signature of the pseudogap that is present above the superconducting transition temperature . This abrupt drop is strongly reduced at fields of 4 and 8 T, as shown by the arrows. A sketch of the sample geometry chosen for the tunneling of the spin-polarized quasiparticles along the -axis is shown in the inset. The film thicknesses were 300 and 50 nm for the YBCO layers and the LSMO, respectively.
The pseudogap closing field and follow a simple Zeeman scale, . Here is the Bohr magnetron constant and is the Boltzmann constant.
MR effect in YBCO/LSMO/YBCO structures in fields up to 5 T at 140 K . Note that the magnetization vectors switch from antiparallel to parallel at some critical field around 0.7 T.
MR effect in YBCO/LSMO/YBCO structures in fields up to 8 T at 240 K . The magnetization vectors switch fully from antiparallel to parallel at some critical field around 2 T (marked by the arrow), and the MR becomes constant.
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