Dr. Daniel Urban deutschenglish  

  That's me!  

Physikalisches Institut
Hermann-Herder-Str. 3
79104 Freiburg

E-mail: daniel.urban@iwm.fraunhofer.de

 

   



  Research Topics deutschenglish  

  My research interests are within the field of electron transport in nanostructures. When the system size approaches the nano scale, quantum mechanical effects become important and start to dominate over the ''classical physics'' that we are custom with from every-day life. Besides a fundamental interest in these quantum phenomena they are foreseen to become essential to prospective nanoelectronic devices and fundamental to a possible realization of a quantum computer in the future.
During my PhD I examined metallic nanowires, 3-dimensional wires with a diameter of only a few atoms thickness. The remarkable stability of these ''ultimate'' conductors turned out to be due to a particular electronic shell filling, an archetype of a quantum size effect. With a comprehensive stability analysis we could relate the experimentally observed quantized conductance values with the energetically favourable geometric configurations of the nanowires and shed light on their interplay with symmetry breaking deformations and scaling laws.
Subsequently I started to study the noise properties of mesoscopic conductors. Current and charge fluctuations contain various informations on the system and the underlying interactions. Since the higher order moments of the distribution of transmitted charges through a conductor are small and hard to observe experimentally, effective detectors have to be designed and respective theoretical models have to be developed. Here I worked on the theory of the Josephson junction threshold detector and on the problem of heating effect through phonons on the full counting statistics of a molecular junction or atomic wire.
In parallel, I recently started the study of two dimensional lattice systems which can be described by a Dirac-like equation of a pseudo spin 1. These lattices are in some respect similar to graphene (described by a pseudo-spin 1/2 Dirac equation) but generalize this concept to the realm of integer spin and show a number of new and interesting aspects. We investigate these lattices also in the perspective of the emergence of topological states of matter.

My current line of research includes
  • Electron Transport in Nanostructures
  • Noise Properties of Mesoscopic Conductors (full counting statistics)
  • Quantum transport out of equilibrium
  • Graphene and related lattice systems of pseudo spin 1
  • Topological states of matter
 



Publications

 
2013
Adiabatic pumping in the quasi-one-dimensional triangle lattice
M. Schulze, D. Bercioux, D. F. Urban, Phys. Rev. B 87, p. 024301 (2013)
Rashba spin-orbit interaction in graphene armchair nanoribbons
L. Lenz, D. F. Urban, &; D. Bercioux, The European Physical Journal B 36, p. 502 (2013)
2012
Rashba spin-orbit-interaction-based quantum pump in graphene
D. Bercioux, D. F. Urban, F. Romeo, R. Citro, Applied Physics Letters 101, p. 122405 (2012)
Finite frequency noise properties of the non-equilibrium Anderson impurity model
C. P. Orth, D. F. Urban and A. Komnik, Phys. Rev. B 86, p. 125324 (2012)
2011
Anderson impurity model in nonequilibrium: analytical results versus quantum Monte Carlo data
L. Mühlbacher, D. F. Urban, A. Komnik, Phys. Rev. B 83, p. 075107 (2011)
Topology-induced phase transitions in quantum spin Hall lattices
D. Bercioux, N. Goldman, and D.F. Urban, Phys. Rev. A 83, p. 023609 (2011)
Topological Phases for Fermionic Cold Atoms on the Lieb Lattice
N. Goldman, D. F. Urban, D. Bercioux, Phys. Rev. A 83, p. 063601 (2011)
Barrier transmission of Dirac-like pseudospin-one particles
D. F. Urban, D. Bercioux, M. Wimmer, W. Häusler, Phys. Rev. B, 84, p. 115136 (2011)
2010
Nonlinear effects of phonon fluctuations on transport through nanoscale junctions
D. F. Urban, R. Avriller, and A. Levy Yeyati, Phys. Rev. B 82, p. 121414 (R) (2010)
The Nanoscale Free-Electron Model
D. F. Urban, J. Bürki, C. A. Stafford, and H. Grabert, Handbook of Nanophysics (Ed. K. Sattler), Taylor & Francis (2010)
2009
Feedback and Rate Asymmetry of the Josephson Junction Noise Detector
D. F. Urban and H. Grabert, Phys. Rev. B 79, p. 113102 (2009)
Massless Dirac-Weyl Fermions in a T3 Optical Lattice
D. Bercioux, D. F. Urban, H. Grabert, W. Häusler, Phys. Rev. A 80, p. 063603 (2009)
2008
Interaction-induced beats of Friedel oscillations in quantum wires
D. F. Urban and A. Komnik, Phys. Rev. Lett. 100, p. 146602 (2008)
2007
Scaling Theory of the Peierls-CDW in Metal Nanowires
D. F. Urban, C. A. Stafford, and H. Grabert, Phys. Rev. B 75, p. 205428 (2007)
Electronic and atomic shell structure in aluminum nanowires
A. I. Mares, D. F. Urban, J. Bürki, H. Grabert, C. A. Stafford, J. M. van Ruitenbeek, Nanotechnology 18, p. 265403 (2007)
2006
Stability and symmetry breaking in metal nanowires: The nanoscale free-electron model
D. F. Urban, J. Bürki, C. A. Stafford, H. Grabert, Phys. Rev. B 74, p. 245414 (2006)
2004
Electronic shell effects and the stability of alkali nanowires
D. F. Urban, J. Bürki, A. I. Yanson,I. K. Yanson, C. A. Stafford, J. M. van Ruitenbeek, H. Grabert, Solid State Comm. 131, p. 609 (2004)
Jahn-Teller Distortions and the Supershell Effect in Metal Nanowires
D. F. Urban, J. Bürki, C.-H. Zhang, C. A. Stafford, and H. Grabert, Phys. Rev. Lett. 93, p. 186403 (2004)
2003
Interplay of Rayleigh and Peierls Instabilities in Metallic Nanowires
D. F. Urban and H. Grabert, Phys. Rev. Lett. 91, p. 256803 (2003)



  Curriculum Vitae deutschenglish  

  1994   Abitur at the Hochrheingymnasium (highschool) in Waldshut  
  1994 - 1999   Studies of physics at the University of Freiburg  
  1997 - 2002   Fellowship of the Studienstiftung des deutschen Volkes  
  1997 - 1998   Studies of physics at the Université Paris Sud XI, Orsay  
  1997 - 1998   Fellowship of the Dr. Jürgen Ulderup Foundation  
  2001 - 2002   Diploma-thesis in the theoretical solid state physics group of Prof. H. Grabert
Subject: Stability analysis of metallic nanowires
 
  2003   Gustav-Mie-Award of the University of Freiburg for the best Diploma-thesis 2002  
  2002 - 2006   PhD studies in the theoretical solid state physics group of Prof. H. Grabert
Subject: Stability, Symmetry Breaking, and Scaling Properties of Metallic Nanowires
 
  2002 - 2006   Associate member of the EU research and training network DIENOW  
  2-3/2004   1st research stay at the Department of Physics, University of Arizona, USA  
  2-3/2005   2nd research stay at the Department of Physics, University of Arizona, USA  
  2006 - present   Postdoctoral Research Associate at the Albert-Ludwig University Freiburg  
  2008   Pfizer Award for young researchers  
  2-9/2009   Research stay at the Universidad Autonoma de Madrid, Spain