Events

Pablo Garcia Campos presents

Visualization of the Intermediate state in PdTe2 and of the Chiral superconductivity in UPt3 with SQUID microscopy 

Monday 20th December 2021 at 11:00 am

Seminar room, Building A, Institut Néel : number of person limited to 30 

Lien visio : https://univ-grenoble-alpes-fr.zoom.us/j/96320324632?pwd=RjFFQjhvZWwyaDVlWityaUxVdkZrZz09

Meeting ID : 963 2032 4632
Pass code : 515965

The presentation and the slides will be in English.

Abstract :

Symmetry and topology are tools to describe states of quantum matter.
Dirac cones in the band structure of the semimetal PdTe2 may induce topological state and be at the origin of the superconductivity of this compound (Tc=1.64 K and μ0Hc=13.6 mT). Thermodynamic and muon spin rotation experiments support type-I superconductivity, which is unusual for a binary compound. STM and Point-Contact Spectroscopy measurements, however, show the existence of type-II superconductivity. A key property of a type-I superconductor is the intermediate state, which presents coexistence of superconducting and normal domains at magnetic fields lower than the thermodynamic critical field Hc. I will present scanning SQUID microscopy studies revealing coexisting superconducting and normal domains of tubular and laminar shape as the magnetic field is more and more increased, thus confirming type-I superconductivity in PdTe2.

UPt3 is a model compound for  unconventional superconductivity where additional symmetries to the gauge symmetry are broken. UPt3 ( Tc= 0.55 K) is the only material known to present three different superconducting phases. The boundary between the A and the chiral B phases is crossed upon cooling in zero field at 0.5 K. In the B phase, two energetically degenerated chiral domains, which break time-reversal symmetry, may coexist. Theoretical predictions propose the existence of fractional vortices and an unusual flux distribution at the domain wall separating chiral domains. I will present SQUID microscopy results reporting the observations of the alignment of the magnetic flux with the domain walls and the existence of half-Ф0 vortices.

Supervisor : 
Klaus Hasselbach

Jury’s Members :
Mme. BEENA KALISKY  Professeur associé  Bar-Ilan University  Rapportrice
M. HERMANN SUDEROW  Professeur associé  Universidad Autónoma de Madrid Rapporteur
M. THIERRY KLEIN  Professeur des Universités  Université Grenoble-Alpes  Examinateur
M. MANUEL HOUZET  Ingénieur HDR  CEA Centre de Grenoble Examinateur
M. YANN GALLAIS  Professeur des Universités  Université de Paris  Examinateur