Highlights & News

Atomic force micrograph of NaCl

AFM micrograph of NaCl November 2013 – We have upgraded our LT-STM with new wiring and spring suspension. During the system commissioning, atomic resolution of NaCl has been demonstrated.

Phys. Rev. B

Bi-Si vacancy pair July 2013 – In this study, we find that isolated heavy dopants behave entirely different at the surface compared to the bulk and to lighter dopants. The common light impurity P replaces individual Si atoms and maintains the integrity of the dimer superstructure of the Si(001) surface, but loses its valence electrons to surface states. In contrast, we find that Bi atoms form pairs with Si vacancies, retain their electrons, and have highly localized, half-filled orbitals. This result strikingly shows that the basic properties of dopants at surfaces and interfaces are not solely governed by their column of origin as they are in the bulk. Collaboration with the LCN. MORE...

PhD Degree - Congratulations

Bianco PhD defence May 2013 – Congratulations to François Bianco who obtained his PhD degree, May 7, 2013. Toutes nos félicitations Dr Bianco! Picture L.Windels

ACS Nano

Haiku hydrogen dangling bon row April 2013 – Hydrogen dangling bonds are highly reactive and their selective exposure on hydrogenated Si(001) using scanning probes is developing as a powerful lithography to pattern molecules and atoms. We have found that hydrogen is more weakly bound along the centre of Haiku stripes, thus offering a new, fully scalable thermodynamic route to produce very long dangling bond rows in large numbers to self-assemble long chains of atoms and molecules. Our STM study further reveals an unexpected flat dimer configuration, possibly stabilized by the local strain induced by the Haiku core structure. MORE...

New Instrument

JT-STM March 2013 – First high quality atomic micrographs obtained with our new Joule-Thomson STM from SPECS installed last September.

APS Member Elect

Maria Longobardi December 2012 - Congratulations to Dr. Maria Longobardi who has been elected as an International Student Affairs Officer of the American Physical Society. The ISA Officer chairs the International Student Affairs Committee. She will serve as the principal point of contact between the Forum and similar organizations in countries outside the United States and will act as a student advocate for international student issues to the American Physical Society. FGSA-sponsored international activities, including conferences and student issues, will be reported annually by the ISA Officer to both the FGSA Executive Board and the APS Director of International Affairs. Maria will serve a three-year term.

New Instrument

JT-STM September 2012 – A new Joule-Thomson scanning tunneling microscope from SPECS has been installed and is currently being tested.

SPS 2012 Poster Award

François Bianco June 2012 – Congratulations to François Bianco who has received an EPL best poster award at the 2012 meeting of the Swiss Physical Society in Zürich.

PRL - Editor's suggestion

Piezoresistance June 2012 – Measuring the piezoresistance in p-type silicon up to 3GPa, we found it to decrease with compressive stress beyond the predicted saturation. This result has potential implications for the Si technology roadmap. Collaboration with Ecole Polytechnique Palaiseau and IEMN. Article featured in EE Times News&Analysis. MORE...

Subside Tremplin 2012

Maria Longobardi May 2012 – Congratulations to Dr. Maria Longobardi who has been awarded a subside tremplin 2012 by the University of Geneva.

Magic weather

STM head February 2012 - Temperatures below -10°C and strong winds have united to produce amazing pieces of art along lake Geneva, here in Versoix.

Nature Communications - featured image

Model of CaC6 November 2011 – One dimensional charge density wave discovered by scanning tunneling microscopy in CaC6, a superconducting graphite intercalate compound. Collaboration with the LCN. MORE...

Supra100

Supra100 September 2011 - MaNEP and the University of Geneva are celebrating 100 years of superconductivity. MORE...

Physical Review B

Electronic 1D state along the Haiku core July 2011 – A one dimensional electronic state has been uncovered along the core of a self assembled endotaxial Si nanoline at the Si(001):H surface, with a range of promising properties to explore 1D physics. MORE...

J.Phys.:Cond.Mat. - IOPSELECT

MnSi nanowires on Si(001) May 2011 – The anisotropic surface stress induced by Bi-nanolines is found to block the formation of embedded structures and stabilizes the nucleation of manganese silicide islands which grow in a preferred direction, forming nanowires on Si(001). MORE...

Nature Communications - featured image

Mobile oxygen adatoms and defects at a bilayer manganite surface March 2011 – The oxygen migration scenario for electroresistive switching in manganites gets new support. Mobile oxygen adatoms and defects have been observed by scanning tunneling microscopy with atomic resolution at the surface of PrSr2Mn2O7. Collaboration with the LCN. MORE...

PRL - Editor's suggestion

Giant Piezoresistance Effects in Silicon Nanowires and Microwires November 2010 - Migrating surface charges can simulate the giant piezoresistance observed in silicon nano- and micro-structures. See also comments in APS Physics Synopsis ; Nature Materials Research Highlight and Physics World News. MORE...

Applied Physics Letters

Artistic view of the Si only template (red) with a green atomic chain on top of it September 2010 – A promising Silicon only template for nanoscale patterning has been self assembled into the Si(001) surface. This work has been selected by the Virtual Journal of Nanoscale Science & Technology . MORE...

Subside Tremplin 2010

Sigrun A. Köster May 2010 – Congratulations to Dr. Sigrun A.Köster who has been awarded a subside tremplin 2010 by the University of Geneva.

Nature Materials

Logo PhysiScope April 2009 – The PhysiScope draws the attention of Nature Materials. See also the Editorial . MORE...

Physical Review Letters

Giant piezoresistance April 2008 – Giant piezoresistance observed in a metal silicon hybrid structure. See also Physics News Update . MORE...

Archives

Overview

Our research is focused on low dimensional physics and correlated electron systems. Current scientific projects include i) The fabrication of a truly one dimensional model system; ii) Probing the exotic electronic quantum properties emerging in reduced dimensionalities (1D and 2D); iii) Understanding the interplay between ordered electronic phases and superconductivity. These questions are investigated on self-assembled single atom wires on silicon, graphitic materials, dichalcogenides, iron pnictides and specifically designed functional electronic systems.

The prime experimental techniques are scanning tunneling microscopy (STM) and spectroscopy (STS) in combination with atomic force microscopy (AFM). We are operating two commercial instruments combining STM and AFM in ultrahigh vacuum (UHV) and variable temperature. The Omicron LT-STM is equipped with RHEED, LEED, XPS, a dedicated hydrogen cracker, an ion gun and a range of deposition sources. The SPECS JT-STM is equiped with a dedicated hydrogen cracker, an ion gun and a range of deposition sources. A 3 Tesla magnetic field shall be added to the JT-STM in 2013. A third UHV variable temperature system with magnetic field, specifically designed for spin polarized studies, is under development.

We are also actively developing the scanning probe technique itself, building a scan head with increased functionalities, a novel scheme to detect the spin polarization of the tunneling electrons by STM and an all electric cantilever deflection sensors.