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Published on: August 2, 2019
Superconductivity versus quantum criticality: what can we learn from heavy fermions?
F Steglich1, J Arndt, S Friedemann
1Max Planck Institut für Chemische Physik fester Stoffe, Nöthnitzer Strasse 40, D-01187 Dresden, Germany. steglich@cpfs.mpg.de
Summary
Two quantum critical point scenarios exist for antiferromagnetic heavy-fermion systems. Studies compare CeCu2Si2 and YbRh2Si2, revealing distinct behaviors related to superconductivity, with implications for understanding quantum criticality.
Area of Science:
- Condensed Matter Physics
- Quantum Materials Science
Background:
- Antiferromagnetic (AF) heavy-fermion (HF) systems exhibit complex quantum critical point (QCP) behaviors.
- Two main scenarios are proposed: itinerant spin-density wave (SDW) QCPs and Kondo-destroying QCPs.
Purpose of the Study:
- To investigate and compare two distinct QCP scenarios in isostructural HF compounds.
- To explore the relationship between QCP nature and superconductivity (SC) in these systems.
Main Methods:
- Comparative study of CeCu2Si2 and YbRh2Si2.
- Utilizing inelastic neutron scattering experiments.
- Employing chemical pressure via partial substitution (Ir or Co for Rh) in YbRh2Si2.
Main Results:
- CeCu2Si2 exhibits a 3D SDW QCP with associated superconductivity.
- YbRh2Si2 shows an AF QCP coinciding with a Kondo-destroying QCP, which can be tuned.
- Superconductivity is absent in YbRh2Si2 down to millikelvin temperatures.
Conclusions:
- The nature of the QCP significantly influences the occurrence of superconductivity in HF systems.
- Further studies on other HF superconductors are needed to confirm the correlation between QCP type and SC.
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