Hybridization-Controlled Pseudogap State in the Quantum Critical Superconductor CeCoIn5

Abstract

The origin of the partial suppression of the electronic density states in the enigmatic pseudogap behavior, which is at the core of understanding high-$T_c$ superconductivity, has been hotly contested as either a hallmark of preformed Cooper pairs or an incipient order of competing interactions nearby. Here, we report the quasi-particle scattering spectroscopy of the quantum critical superconductor CeCoIn${}_5$, where a pseudogap with energy ${\Delta }_g$ was manifested as a dip in the differential conductance ($dI/dV$) below the characteristic temperature of $T_g$. When subjected to external pressure, $T_g$ and ${\Delta }_g$ gradually increase, following the trend of increase in quantum entangled hybridization between Ce 4$f$ moment and conduction electrons. On the other hand, the superconducting (SC) energy gap and its phase transition temperature shows a maximum, revealing a dome shape under pressure. The disparate dependence on pressure between the two quantum states shows that the pseudogap is less likely involved in the formation of SC Cooper pairs, but rather is controlled by Kondo hybridization, indicating that a novel type of pseudogap is realized in CeCoIn${}_5$.

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References in corpus (14)

• Scanning tunneling spectroscopy of high-temperature superconductors
• Lattice symmetry breaking in cuprate superconductors: Stripes, nematics, and superconductivity
• Andreev Reflection in Heavy-Fermion Superconductors and Order Parameter Symmetry in CeCoIn_5
• Electron Cotunneling into a Kondo Lattice
• Universal Behavior in Heavy Electron Materials
• Pseudogap phase of cuprate superconductors confined by Fermi surface topology
• The Fano effect in the point contact spectroscopy of heavy electron materials
• Structural investigations of CeIrIn${}_5$ and CeCoIn${}_5$ on macroscopic and atomic length scales
• Nature of the spin resonance mode in CeCoIn${}_5$
• Two-channel point-contact tunneling theory of superconductors
• Experimental verification of contact-size estimates in point-contact spectroscopy on superconductor/ferromagnet heterocontacts
• Spectroscopic Evidence for the Direct Involvement of Local Moments in the Pairing Process of the Heavy-Fermion Superconductor CeCoIn${}_5$
• The Lorenz number in CeCoIn${}_5$ inferred from the thermal and charge Hall currents
• Origin of gap-like behaviors in URu${}_2$Si${}_2$: Combined study via quasiparticle scattering spectroscopy and resistivity measurements