Giant anisotropy of the resistance induced by magnetic domains in superconductor/ferromagnet hybrids

We experimentally studied the magnetoresistance of a superconducting Al microbridge fabricated on top of a ferromagnetic BaFe₁₂O₁₉ single crystal. Due to the presence of a one-dimensional domain structure in the ferromagnetic substrate, the superconducting critical temperature reaches its maximal value at the compensation field, |H|?B₀$|H|?B_0$, when superconductivity nucleates above magnetic domains of opposite polarity with respect to the applied magnetic field H   (so-called reverse-domain superconductivity, B₀$B_0$ being the amplitude of the z-component of the nonuniform magnetic field). Such localized superconductivity makes it possible to transfer superconducting currents without dissipation only along the magnetic domains, leading to a pronounced anisotropy of the resistance of this system at low temperatures.