  We investigate the unusual phase transitions in SrRuO$_{3}$ and
Sr$_{0.5}$Ca$_{0.5}$Ru$_{1-x}$Cr$_{x}$O$_{3}$ (x=0,0.05 and 0.1) employing
x-ray diffraction, resistivity, magnetic studies and x-ray photoemission
spectroscopy. Our results show the compounds undergo crossover from $itinerant$
ferromagnetism to $localised$ ferromagnetism. The combined studies suggests Ru
and Cr to be in 4+ valence state. A Griffith phase and an enhancement in Curie
temperature (Tc) from 38 K to 107 K is observed with Cr doping. A shift in the
chemical potential towards the valence band is observed with Cr doping. In the
metallic samples, interestingly, a direct link between the resistivity and
orthorhombic strain is observed. Detailed studies in this direction will be
helpful to understand the nature of interactions and hence manoeuvre its
properties. In the non metallic samples, the resistivity is mainly governed by
disorder and electron-electron correlation effects. The value of the
resistivity for the 5% Cr doped sample suggests semi metallic behaviour.
Understanding its nature in detail using electron spectroscopic techniques
could unravel the possibility of its utility in high mobility transistors at
room temperature and its combined property with ferromagnetism will be helpful
in making spintronic devices.
