P. Nedellec et al., INHOMOGENEOUS MAGNESIUM HYDRIDE SYNTHESIZED BY LOW-TEMPERATURE ION-IMPLANTATION - WEAK-LOCALIZATION EFFECT, Journal de physique. I, 3(11), 1993, pp. 2285-2297
Metastable MgH(x) hydride was prepared by H ion implantation into Mg f
ilms at 5 K. The resistivity and magnetoresistance temperature depende
nce reveal weak localization effects due to atomic disorder. At low hy
drogen concentrations, x less-than-or-equal-to 0.3, the conductivity v
aries as sigma is similar to log(T), typical of two-dimensional weak l
ocalization behaviour. The resistivity is also very sensitive to the s
ample inhomogeneity, due to H diffusion, which can be modelled by intr
oducing a temperature-dependent geometrical percolating factor G. At h
igher H concentrations, 0.7 less-than-or-equal-to x less-than-or-equal
-to 3, after annealing at 20 K, 50 K and 110 K, the samples also exhib
it weak localization but with three-dimensional behaviour i.e. sigma i
s similar to square-root T. Our analysis is consistent with the existe
nce of an inhomogeneous system formed by a mixture of two phases with
contrasted conduction properties, one of which is a well-behaved metal
, while the other displays the localization properties. The results le
ad us to identify the former phase to a non percolating superconductin
g phase at low temperature.