First-order spin-paramagnetic transition and tricritical point in ultrathin Be films

P. Adams, Louisiana State University
P. Herron, Louisiana State University
E. Meletis, Louisiana State University


We report measurements of the parallel critical magnetic field of thin superconducting beryllium films with (Formula presented) The critical field transitions were spin-paramagnetically limited and found to be strongly hysteretic below a tricritical point at (Formula presented) The magnitude of the hysteresis and (Formula presented) were observed to be completely suppressed in field misalignments (Formula presented) Time relaxation measurements in the hysteretic regime showed simple exponential decays in the highest quality films and nonexponential decays interspersed with avalanches in more inhomogeneous samples. © 1998 The American Physical Society.