• Morenzoni, E.
• Li, L.
• Petrovic, Cedomir
• Guguchia, Z.
• Biswas, P. K.
• Khasanov, R.
• Wang, K.
• Krieger, J. A.

Abstract

<jats:title>Abstract</jats:title><jats:p>We report microscopic studies by muon spin spectroscopy of the superconducting properties as a function of chemical and hydrostatic pressure in the cubic ternary intermetallic (Ca<jats:sub><jats:italic>x</jats:italic></jats:sub>Sr<jats:sub>1−<jats:italic>x</jats:italic></jats:sub>)<jats:sub>3</jats:sub>Rh<jats:sub>4</jats:sub>Sn<jats:sub>13</jats:sub> compounds. We find evidence of a quantum critical point at a critical pressure p<jats:sub><jats:italic>c</jats:italic></jats:sub> in the superconducting phase, where the superfluid density increases by a factor of two and the superconducting pairing strength displays a pronounced maximum. The enhancement of superconductivity is related to the structural phase transition at p<jats:sub><jats:italic>c</jats:italic></jats:sub>, which is accompanied by profound changes of the Fermi surface associated to the suppression of a charge density wave (CDW). The quantum critical point separates a superconducting phase coexisting with CDW from a pure superconducting phase, while in both phases superconductivity has a strong-coupling phonon-mediated BCS-like s-wave character. Together with the related isoelectronic compound (Ca<jats:sub><jats:italic>x</jats:italic></jats:sub>Sr<jats:sub>1−<jats:italic>x</jats:italic></jats:sub>)<jats:sub>3</jats:sub>Ir<jats:sub>4</jats:sub>Sn<jats:sub>13</jats:sub>, this system shows that conventional BCS superconductors in the presence of competing orders may display behaviour and characteristics of unconventional superconductors.</jats:p>

Topics

• density
• impedance spectroscopy
• surface
• compound
• phase
• strength
• phase transition
• intermetallic
• superconductivity
• superconductivity