Evidence for quantum mesoscopic tunneling in rare-earth layers

Abstract

We report on finite size effects and evidence for quantum mesoscopic tunneling (QMT) in thin isolated rare-earth layers prepared in the form of R/Mo multilayers where R represents Tb, Dy, or Dy50Co50. The magnetic transition temperature Tc decreases with decreasing magnetic layer thickness and is discussed within a finite size scaling theory. Evidence for QMT is found in magnetic relaxation measurements in these systems with a sharp crossover to a temperature-independent magnetic relaxation regime at low temperatures. The Tb system has a crossover temperature T0 of 20 K, the largest value reported so far for this crossover.