  In this work we measure and study the cross-correlation signal between a
foreground sample of GAMA galaxies with spectroscopic redshifts in the range
$0.2<z<0.8$, and a background sample of H-ATLAS galaxies with photometric
redshifts $\gtrsim1.2$. It constitutes a substantial improvement over the
cross-correlation measurements made by Gonzalez-Nuevo et al. (2014) with
updated catalogues and wider area (with $S/N\gtrsim 5$ below 10' and reaching
$S/N\sim 20$ below 30"). The better statistics allow us to split the sample in
different redshift bins and to perform a tomographic analysis (with $S/N\gtrsim
3$ below 10 arcmin and reaching $S/N\sim 15$ below 30"). Moreover, we implement
a halo model to extract astrophysical information about the background galaxies
and the deflectors that are producing the lensing link between the foreground
(lenses) and background (sources) samples. In the case of the sources, we find
typical mass values in agreement with previous studies: a minimum halo mass to
host a central galaxy, $M_{min}\sim 10^{12.26} M_\odot$, and a pivot halo mass
to have at least one sub-halo satellite, $M_1\sim 10^{12.84} M_\odot$. However,
the lenses are massive galaxies or even galaxy groups/clusters, with minimum
mass of $M_{min}^{lens}\sim 10^{13.06} M_\odot$. Above a mass of
$M_1^{lens}\sim 10^{14.57} M_\odot$ they contain at least one additional
satellite galaxy which contributes to the lensing effect. The tomographic
analysis shows that, while $M_1^{lens}$ is almost redshift independent, there
is a clear evolution of increase $M_{min}^{lens}$ with redshift in agreement
with theoretical estimations. Finally, the halo modeling allows us to identify
a strong lensing contribution to the cross-correlation for angular scales below
30". This interpretation is supported by the results of basic but effective
simulations.
