Agenda

Next Quantum Material Seminar:

Friday, December 16th 2022 at 11:00 am

F. Malte Grosche  (Cavendish Laboratory, Cambridge UK)

“ Narrow bands and dissipation in quantum materials”

To access this seminar:

Institut Néel CNRS, Building E, 3rd floor, Room Nevill Mott  (E424)

Abstract: Whereas fine-tuning to a quantum critical point leads to long-lived excitations in tightly defined regions of parameter space, narrow bands may more generally be caused by built-in mechanisms:

If a continuous structural phase transition is suppressed to low temperatures, low-energy vibrational excitations can arise that boost superconductivity and cause a linearly temperature dependent electrical resistivity. In aperiodic host-guest structures, such as that found in high-pressure bismuth, very similar phenomena extend over a wide pressure range, suggesting that a low-energy sliding phonon mode is built in. Phonon damping appears to be essential for thermodynamic and transport properties in these materials.

On-site electronic interactions can cause strong electronic mass renormalisation and narrow electronic bands without fine-tuning. Quantum oscillation measurements resolve the electronic Fermi surface and carrier mass in the pressure-metallised Mott insulator NiS2 and in the Fe-based superconductor YFe2Ge2, enabling detailed comparison with theoretical scenarios.

The interplay between local mechanisms and fine-tuning to a quantum critical point is explored in the Kondo lattice system CeSb2 [3], which superconducts over a narrow pressure range at magnetic fields that exceed the Pauli limit by nearly an order of magnitude.

The organizers:

Elsa Lhotel (elsa.lhotel@neel.cnrs.fr)
Florence Levy-Bertrand (florence.levy-bertrand@neel.cnrs.fr)