Abstract
We study the onset of the irreversible magnetic behavior of vortex matter in micron-sized single crystals by using silicon micro-oscillators. We find an irreversibility line appearing well below the thermodynamic Bragg-glass melting line at a magnetic field which increases both with increasing the sample radius and with decreasing the temperature, paradoxically implying the existence of a reversible vortex solid. We show that at this irreversibility line, the sample radius can be identified with the crossover length between the Larkin and the random-manifold regimes of the vortex-lattice transverse roughness. Our method thus allows to determine, as a function of temperature and applied magnetic field, the minimum size of a vortex system that can be collectively pinned, or the so-called three-dimensional weak collective pinning Larkin radius, in a direct way.
- Received 21 August 2009
DOI:https://doi.org/10.1103/PhysRevB.81.092502
©2010 American Physical Society