Published online by Cambridge University Press: 15 February 1998
Thin films of ${\rm Cu_2Mo_6S_8}$ have been in-situ deposited by pulsed laser
deposition on R-plane ${\rm Al_2O_3}$
on which an epitaxial growth has been achieved for the first
time, with the $(100)_R$
orientation, as
shown by X-ray diffraction. The superconducting
transition temperature has been determined
from DC resistive and AC susceptibility
measurements. The critical temperature Tc is typically
between 9.5 and 10.3 K and the
transitions are narrow: the full width at half
maximum of the inductive signal $\chi ''$
ranges
between 0.1 and 0.5 K. The critical current densities have been obtained by standard
four probe electrical measurements: in zero field a value larger than
$10^8\; {\rm A}/{\rm m}^2$
has been
measured at only 1 K from the end of the transition, and values typically larger than
$10^7\;{\rm A}/{\rm m}^2$
at 4.2 K in an applied magnetic field of 7 T have been observed. The upper
critical magnetic field, Bc2, has been determined from the critical current measurements
performed at 4.2 K in an applied magnetic field, for two samples. The experimental
values of 11 and 12.5 T at 4.2 K are close to those reported on bulk samples (12.5 T).
For the first time to our knowledge a surface resistance $(R_{\rm s})$
measurement has been
carried out on a Chevrel phase-type compound: a value of
4.5 mΩ at 10 GHz and 4.2 K has been obtained.
In honour of Dr. Jean Padiou on the occasion of his retirement. This paper was presented at "5es Journées de Cryogénie et de Supraconductivité" held at Aussois in April 1997.
* In honour of Dr. Jean Padiou on the occasion of his retirement. This paper was presented at "5es Journées de Cryogénie et de Supraconductivité" held at Aussois in April 1997.