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Field Induced Fermi Surface Instabilities in Heavy Fermion Systems

Mardi 19 juin 11:00 - Duree : 1 heure
Lieu : LNCMI, salle de conférences "René Pauthenet" (bâtiment J, 2ème étage) - 25 rue des martyrs - 38000 Grenoble

Orateur : Alexandre POURRET (IMAPEC-PHELIQS-INAC CEA Grenoble)

The quantum phase transitions from magnetic phases (anti-ferromagnetic (AF) or ferromagnetic (FM)) to paramagnetic (PM) or polarized paramagnetic ground states (PPM) have been poorly discussed in term of Fermi surface reconstruction but mainly in the frame- work of Kondo/RKKY interactions and itinerant spin fluctuations. Nevertheless, Fermi surface (FS) instabilities, such as Lifshitz transitions, which have been neglected in mean field theories has recently been mentioned as a driving force to modify the ground-state properties in correlated electron systems such as cuprates, pnictides and heavy fermion materials. Due to the strong quasiparticle renormalization, the latter possess flat bands close to the Fermi level often accompanied with van-Hove singularities in the renormalized density of state (DOS). Theses flat bands are extremely sensitive to external parameters such as doping, pressure or magnetic field. In particular, field induced Lifshitz transitions have been identified in an increasing number of systems. I will present recent results in the AF compound YbRh2Si2 [1] and in the FM compound UCoGe [2] where a cascade of field induced Lifshitz transitions has been observed in different transport properties such as resistivity, Hall effect and thermoelectric power. Similarly, very recent thermoelectric measurements in the AF superconductor UPd2Al3 show a succession of anomalies, see Fig. 1, on a large magnetic field range 4-16T below the metamagnetic transition (which occurs at HM=18T). This is undoubtedly the sign of a field induced cascade of Lifshitz transition.

References

1.A. Pourret, et al., J. Phys. Soc. Jpn. 82, 053704 (2013)

2. B. Gaël, et al., Phys. Rev. Lett. 117, 206401 (2016)

Contact : anne-laure.barra@lncmi.cnrs.fr

Discipline évènement : (Physique)
Entité organisatrice : (LNCMI)
Nature évènement : (Séminaire)
Evènement répétitif : (Séminaire LNCMI)
Site de l'évènement : Polygone scientifique

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