We present electrical transport, magnetization, and ac as well as dc magnetic susceptibility measurements of the highly anisotropic compound LaSb${}_2$. Our data display a very broad anisotropic transition upon cooling below 2.5 K into a clean superconducting state with a field-dependent magnetization that is consistent with type I behavior. We identify distinct features of two-dimensionality in both the transport and magnetic properties. Application of hydrostatic pressure induces a two- to three-dimensional crossover evidenced by a reduced anisotropy and transition width. The superconducting transition appears phase-fluctuation-limited at ambient pressure, with fluctuations observed for temperatures greater than eight times the superconducting critical temperature.

• Received 4 March 2011

DOI:https://doi.org/10.1103/PhysRevB.83.174520