Spin-paramagnetic transition of ultrathin granular Al films in a tilted magnetic field
Abstract
We report measurements of the critical fields of ultrathin granular Al films as a function of temperature and magnetic-field orientation. Due to the spin-paramagnetic effect, the parallel field (θ=0°) transition becomes first-order and strongly hysteretic below a tricritical point, Ttri∼270 mK. Well below Ttri, the width of the hysteresis collapses according to ΔH(θ)=ΔH(0°)exp(-θ/2.4°) with increasing θ. Our data suggest that the zero-temperature transition goes from first order to second order at θ6.5°. © 1995 The American Physical Society.
This paper has been withdrawn.