• Sharma, Priyamedha
• Takeuchi, Tsunehiro
• Kuga, Kentaro
• Brar, Jaskirat
• Singh, Saurabh

Abstract

<jats:title>Abstract</jats:title><jats:p>We investigate the unusual phase transitions in SrRuO<jats:sub>3</jats:sub> and Sr<jats:sub>0.5</jats:sub>Ca<jats:sub>0.5</jats:sub>Ru<jats:inline-formula><jats:tex-math><?CDATA $_{1-x}$?></jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:msub><mml:mi /><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub></mml:math><jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cmacc15dieqn1.gif" xlink:type="simple" /></jats:inline-formula>Cr<jats:sub><jats:italic>x</jats:italic></jats:sub>O<jats:sub>3</jats:sub> (<jats:italic>x</jats:italic> = 0, 0.05 and 0.1) employing x-ray diffraction, resistivity, magnetic studies and x-ray photoemission spectroscopy. Our results show the compounds undergo a crossover from itinerant ferromagnetism to localized ferromagnetism. The combined studies suggest Ru and Cr be in the 4+ valence state. A Griffith phase and an enhancement in Curie temperature (<jats:italic>T</jats:italic><jats:sub><jats:italic>c</jats:italic></jats:sub>) from 38 K to 107 K are 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. We also observe a connection between orthorhombic strain and <jats:italic>T</jats:italic><jats:sub><jats:italic>c</jats:italic></jats:sub> in all the samples. Detailed studies in this direction will be helpful to choose suitable substrate materials for thin-film/device fabrication and hence manoeuvre its properties. In the non-metallic samples, the resistivity is mainly governed due to disorder, electron-electron correlation effects and a reduction in the number of electrons at the Fermi level. 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.</jats:p>

Topics

• perovskite
• impedance spectroscopy
• compound
• resistivity
• phase
• mobility
• x-ray diffraction
• phase transition
• Curie temperature