Yanick Volpez


Department of Physics
University of Basel
Klingelbergstrasse 82
CH-4056 Basel, Switzerland

email:view address

tel: +41 61 207 36 95

Short CV

2016-present: Ph.D. student in the Condensed Matter Theory & Quantum Computing group at the University of Basel, supervisors: Prof. Klinovaja and Prof. Loss
2015/2016: Master's Thesis: 'Correlated Fermions on Hexagonal Lattices from the Functional Renormalization Group' under the supervision of PD Dr. Michael Scherer
2014-2016: M.Sc. Physics Degree at Heidelberg University
2013/2014: Bachelor's Thesis: 'Calculation of Two-Loop Master Integrals for qq -> VV' under the supervision of Prof. Thomas Gehrmann
2010-2014: B.Sc. Physics Degree at University of Zurich


Show all abstracts.

1.  Three-Dimensional Fractional Topological Insulators in Coupled Rashba Layers
Y. Volpez, D. Loss, and J. Klinovaja.
Phys. Rev. B 96, 085422 (2017)

We propose a model of three-dimensional topological insulators consisting of weakly coupled electron- and hole-gas layers with Rashba spin-orbit interaction stacked along a given axis. We show that in the presence of strong electron-electron interactions the system realizes a fractional strong topological insulator, where the rotational symmetry and condensation energy arguments still allow us to treat the problem as quasi-one-dimensional with bosonization techniques. We also show that if Rashba and Dresselhaus spin-orbit interaction terms are equally strong, by doping the system with magnetic impurities, one can bring it into the Weyl semimetal phase.

2.  Electronic instabilities of the extended Hubbard model on the honeycomb lattice from functional renormalization
Y. Volpez, D. D. Scherer, and M. M. Scherer.
Phys. Rev. B 94, 165107 (2016)

Interacting fermions on the half-filled honeycomb lattice with short-range repulsions have been suggested to host a variety of interesting many-body ground states, e.g., a topological Mott insulator. A number of recent studies of the spinless case in terms of exact diagonalization, the infinite density matrix renormalization group and the functional renormalization group, however, indicate a suppression of the topological Mott insulating phase in the whole range of interaction parameters. Here, we complement the previous studies by investigating the quantum many-body instabilities of the physically relevant case of spin-1/2 fermions with onsite, nearest-neighbor and second-nearest-neighbor repulsion. To this end, we employ the multi-patch functional renormalization group for correlated fermions with refined momentum resolution observing the emergence of an antiferromagnetic spin-density wave and a charge-density wave for dominating onsite and nearest-neighbor repulsions, respectively. For dominating second-nearest neighbor interaction our results favor an ordering tendency towards a charge-modulated ground state over the topological Mott insulating state. The latter evades a stabilization as the leading instability by the additional onsite interaction.