Nanotechnology Now - Press Release: Nanoscale Friction: High Energy Losses in the Vicinity of Charge Density Waves

Home > Press > Nanoscale Friction: High Energy Losses in the Vicinity of Charge Density Waves

An oscillating Atomic Force Microscope tip in proximity to the Charge Density Wave (CDW) on NbSe2 surface. The yellow and blue spheres are the Selenium and Niobium atoms forming the lattice. A single CDW phase slip process is visible onto NbSe2 surface in the vicinity of the tip.

Abstract:
In collaboration with the University of Basel, an international team of researchers has observed a strong energy loss caused by frictional effects in the vicinity of charge density waves. This may have practical significance in the control of nanoscale friction. The results have been published in the scientific journal Nature Materials.

Nanoscale Friction: High Energy Losses in the Vicinity of Charge Density Waves

Basel, Switzerland | Posted on December 15th, 2013

Friction is often seen as an adverse phenomenon that leads to wear and causes energy loss. Conversely, however, too little friction can be a disadvantage as well - for example, running on an icy surface or driving on a wet road.

An understanding of frictional effects is therefore of great importance - particularly in the field of nanotechnology, where friction has to be controlled at a nanoscale. A recent study conducted by researchers from the University of Basel, the University of Warwick, the CNR Institute SPIN in Genoa and the International Centre for Theoretical Physics (ICTP) in Trieste has helped to give a better understanding of how friction works in microscopic dimensions.

In the experiment led by Prof. Dr. Ernst Meyer, Professor of Experimental Physics at the University of Basel, the team vibrated the nanometer-sized tip of an atomic force microscope above the surface of a layered structure of niobium and selenium atoms. They selected this combination due to its unique electronic properties, and in particular the charge-density waves formed at extremely low temperatures. The electrons are no longer evenly distributed as in a metal, but instead form areas where the electron density fluctuates between a high and low range.

Energy losses in the vicinity of charge density waves

The researchers registered very high energy losses in the vicinity of these charge density waves between the surface and the tip of the atomic force microscope, even at relatively large distances of several atomic diameters. "The energy drop was so great, it was as if the tip had suddenly been caught in a viscous fluid," says Meyer.

The team observed this energy loss only at temperatures below 70° Kelvin (-203° C). Since charge density waves do not occur at higher temperatures, it interpreted this as evidence that frictional forces between the probe tip and charge density waves are the cause of the energy loss.

The theoretical model shows that the high energy loss results from a series of local phase shifts in the charge density waves. This newly discovered phenomenon may be of practical significance in the field of nanotechnology, particularly as the frictional effect can be modulated as a function of distance and voltage.

Full bibliographic information

Markus Langer, Marcin Kisiel, Rémy Pawlak, Franco Pellegrini, Giuseppe E. Santoro, Renato Buzio, Andrea Gerbi, Geetha Balakrishnan, Alexis Baratoff, Erio Tosatti and Ernst Meyer
Giant frictional dissipation peaks and charge-density-wave slips at the NbSe2 surface
Nature Materials, published online 15th December 2013 | doi: 10.1038/NMAT3836

####

About Universität Basel
Tradition - The city of Basel is home to the oldest university in Switzerland. Founded upon the initiative of local citizens in 1460, the University of Basel is a modern and attractive centre of teaching, learning, and research situated in the heart of the historic old town.

Self - managed - The University of Basel has been self-managed since 1996 whilst remaining under the jurisdiction of the Cantons of Basel-Stadt and Basel-Landschaft. It provides committed individuals from all over the world with a strong academic community and an inspiring work environment. It is home to 3’500 staff. Its annual budget is approximately 500 million Swiss francs, of which one fourth each is borne by the two sponsoring cantons. The remaining costs are covered through federal contributions, third-party funding, other cantons, and tuition fees.

Full University Status - The University of Basel has full university status. It offers degree programmes across the arts and sciences, ranging from Archaeology to Zoology. One of our distinctive strengths is the focus on «Culture» and «Life Sciences.»

Popular - Comprising 9’000 undergraduate and 2’000 postgraduate and doctoral students, the University of Basel is comparatively small by European standards. Our 320 professors and 1’300 academic staff are dedicated to advancing
knowledge and fostering independent thinking and socially responsible action. We are proud of our high female student roll (55%) – tending upwards – and an increasing number of international students (20%).

Successful - Our mission is to accomplish first-class research, teaching, and public service. We rank among the world’s one hundred best universities and boast a top-ten place among German-speaking universities.

For more information, please click here

Contacts:
Ernst Meyer
University of Basel
Department of Physics
+41 61 267 37 24

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark: