• Singh, Ravi Shankar
• Bansal, Sakshi
• Ali, Asif
• Pant, Himanshu
• Brar, Jaskirat
• Bharath, M.

Abstract

<jats:title>Abstract</jats:title><jats:p>In this work, we have investigated the precursor effects to superconductivity in BaPb<jats:sub>0.75</jats:sub>Bi<jats:sub>0.25</jats:sub>O<jats:sub>3</jats:sub> using temperature dependent resistivity, x-ray diffraction technique and photoemission spectroscopy. The present compound exhibits superconductivity around 11 K (<jats:inline-formula><jats:tex-math><?CDATA $T_{C}$?></jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:msub><mml:mi>T</mml:mi><mml:mrow><mml:mi mathvariant="normal">C</mml:mi></mml:mrow></mml:msub></mml:math><jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cmacabf4ieqn1.gif" xlink:type="simple" /></jats:inline-formula>). The synthesis procedure adopted is much simpler as compared to the procedure available in the literature. In the temperature range (10 K–25 K) i.e. above <jats:inline-formula><jats:tex-math><?CDATA $T_{C}$?></jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:msub><mml:mi>T</mml:mi><mml:mrow><mml:mi mathvariant="normal">C</mml:mi></mml:mrow></mml:msub></mml:math><jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cmacabf4ieqn2.gif" xlink:type="simple" /></jats:inline-formula>, our results show an increase in both the orthorhombic and tetragonal strain. The well screened features observed in Bi and Pb 4<jats:inline-formula><jats:tex-math><?CDATA $f_{7/2}$?></jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"><mml:msub><mml:mi>f</mml:mi><mml:mrow><mml:mn>7</mml:mn><mml:mrow><mml:mo>/</mml:mo></mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:math><jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cmacabf4ieqn3.gif" xlink:type="simple" /></jats:inline-formula> core levels are indicative of the metallic nature of the sample. The compound exhibits finite intensity at the Fermi level at 300 K and this intensity decreases with decrease in temperature and develops into a pseudogap; the energy dependence of the spectral density of states suggests disordered metallic state. Furthermore, our band structure calculations reveal that the structural transition upon Pb doping results in the closing of the band gap at the Fermi level.</jats:p>

Topics

• density
• impedance spectroscopy
• compound
• resistivity
• x-ray diffraction
• band structure
• superconductivity
• superconductivity