E. R. Nowak | Searcharxiv

arXiv2022

Spin-polarized transport in magnetic tunnel junctions with ZnTe barriers

Magnetic tunnel junctions with wide band gap semiconductor ZnTe barrier were fabricated. A very low barrier height and sizable magnetoresistance were observed in the Fe/ZnTe/Fe junctions at room temperature. The nonlinear I-V characteristic curve confirmed the observed magnetoresistance is due to spin-dependent tunneling effect. Temperature dependent study indicated that the total conductance of the junction is dominated by direct tunneling, with only a small portion from the hopping conduction through the defect states inside the barrier.

cond-mat.mes-hall↗

arXiv1996

Slow relaxation in granular compaction

Experimental studies show that the density of a vibrated granular material evolves from a low density initial state into a higher density final steady state. The relaxation towards the final density value follows an inverse logarithmic law. We propose a simple stochastic adsorption-desorption process which captures the essential mechanism underlying this remarkably slow relaxation. As the system approaches its final state, a growing number of beads have to be rearranged to enable a local density increase. In one dimension, this number grows as $N=ρ/(1-ρ)$, and the density increase rate is drastically reduced by a factor $e^{-N}$. Consequently, a logarithmically slow approach to the final state is found $ρ_{\infty}-ρ(t)\cong 1/\ln t$.

cond-mat↗