Theoretical modeling of electrochemically-doped superconducting nanolayers (post-doc)

Axe 4 - Dimensionnalité et confinement

Projet de post-doctorat de Thomas Brumme

Mené du 1er juin 2013 au 31 mai 2014.

Laboratoires co-porteurs

• Institut de minéralogie, de physique des matériaux et de cosmochimie
  Porteur de projet : Matteo Calandra
• Institut des NanoSciences de Paris

Résumé

We developed a first-principles theoretical approach to field-effect doping and the method was implemented in the QuantumEspresso package. The method allows for calculation of the electronic structure as well as complete structural relaxation in field-effect configuration using density-functional theory. Up to now, this was computationally expensive and in some case even impossible. Thus, experimentalists were forced to use simplified screening models in order to determine the induced charge from Hall-effect measurements. Yet, it is unknown to what extend this simple models hold in nanolayers systems and what are the changes which are induced by the large local electric fields (in the order of 1 V/nm).

Scienific results

We described the field-effect doping of nanolayers such as ZrNCl or transition-metal dichalgonides (TMDs). We have shown that, e.g., only one ZrNCl layer is doped and that this induces large structural changes. In TMDs we found only small structural changes. Yet, the correct modeling of the asymmetric electric field proved to be essential. Further-more, we have shown that Hall measurements can overestimate the induced charged.

Publications liées au projet

• Thomas Brumme, Matteo Calandra, Francesco Mauri.
  Electrochemical doping of few-layer ZrNCl from first principles: Electronic and structural properties in field-effect configuration
  Physical Review B : Condensed matter and materials physics, American Physical Society, 2014, 89 (24), pp.245406.
  DOI : 10.1103/PhysRevB.89.245406
  Ref HAL : hal-01502509v1
• Debora Pierucci, Haikel Sediri, Mahdi Hajlaoui, Jean-Christophe Girard, Thomas Brumme et al. 
  Evidence for Flat Bands near the Fermi Level in Epitaxial Rhombohedral Multilayer Graphene
  ACS Nano, American Chemical Society, 2015, 9 (5), pp.5432-5439.
  DOI : 10.1021/acsnano.5b01239〉
  Ref HAL : hal-01240494v1
• Thomas Brumme, Matteo Calandra, Francesco Mauri.
  First-principles theory of field-effect doping in transition-metal dichalcogenides: Structural properties, electronic structure, Hall coefficient, and electrical conductivity
  Physical Review B : Condensed matter and materials physics, American Physical Society, 2015, 91 (15), pp.155436
  DOI : 10.1103/PhysRevB.91.155436
  Ref HAL : hal-01502508v1

Quelques communications

Thommas Brumme a donné  communication à l'étranger dont la principale en 2016 au cours de l'American Physical Society March Meeting 2016, à Baltimore, USA.