Magnetic memory effect in YBa2Cu3O7−x/(BiDy)3(FeGa)5O12 heterostructures

Abstract

YBa 2 Cu 3 O 7−x /(YBCO)(BiDy) 3 (FeGa) 5 O 12 heterostructures have been prepared on ceramic glass substrates by Nd-yttrium–aluminum–garnet pulsed laser ablation. Both YBCO and BiDy-IG garnet layers are found to be polycrystalline without any preferential crystallite orientation. Magnetic hysteresis loop measurements made before and after YBCO deposition reveal perpendicular magnetic anisotropy in the garnet film. The resistance versus temperature measurements indicate that the YBCO layer contains both superconducting and semiconducting phases and exhibits a broad superconducting transition with TC|R=0=22 K. The resistivity of the fabricated heterostructures was found to be very sensitive to external magnetic field and the remnant magnetization of the garnet layer. At 18 K, in a magnetic field of 0.5 T applied perpendicular to the surface of the sample, the magnetoresistance figure of merit ΔR/ΔH reaches the value of 0.26 Ω/Oe and the absolute resistance value of the YBCO channel changes from the mΩ range up to kΩ. In the wide fluctuation temperature range (from 22 to 80 K), the R(T) curve of the YBCO layer is strongly modulated by the remnant magnetization of the garnet layer, clearly exhibiting a magnetic memory effect. A reduction of as much as 9 K in TC|R=0 is observed when the garnet layer has remnant magnetization after having been magnetized. At a measuring current of 1 A/cm2, the output voltage obtainable is in the mV range, which is adequate for use in nonvolatile memory applications.