Mesoscopic noise in disordered FeZr films: Hydrogen clustering and spin-glass effects

In mesoscopic samples of disordered ${\mathrm{Fe}}_{100\mathrm{-}\mathit{x}}$ ${\mathrm{Zr}}_{\mathit{x}}$ evaporated films with x≊8, complex discrete resistance switching due to collective rearrangements of dissolved hydrogen appeared at temperatures from 4 to 300 K. In larger samples, 1% irreproducible hysteretic changes in the resistance as a function of temperature were observed near the nominal ferromagnetic transition, ${\mathit{T}}_{\mathit{C}}$≊250 K, also apparently due to clustering of dissolved H, coupled to the ferromagnetism. The unidirectional anisotropy of the low-temperature reentrant spin-glass magnetic regime was detected via magnetoresistance in mesoscopic samples with hydrogen removed. However, mesoscopic samples exhibiting such anisotropy still showed no detectable spin-glass resistance noise, unlike larger samples.