Lattice effects on the physical properties of half doped perovskite ruthenates

TL;DR

This study explores how lattice effects influence phase transitions and magnetic properties in doped perovskite ruthenates, revealing a crossover from itinerant to localized ferromagnetism and potential applications in spintronics.

Contribution

It provides new insights into the relationship between lattice strain, doping, and magnetic/electronic phase behavior in ruthenates, highlighting the role of Cr doping.

Findings

Curie temperature increases with Cr doping.

Shift in chemical potential observed with doping.

Resistivity linked to orthorhombic strain in metallic samples.

Abstract

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.