Phase transitions driven by competing interactions in low-dimensional systems

¹ Institute of Physical Chemistry, University of Innsbruck - Innsbruck, Austria, EU
² Faculty of Physics, University of Vienna - Vienna, Austria, EU
³ Institute of Applied Physics, Vienna University of Technology - Vienna, Austria, EU
⁴ Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences Innsbruck, Austria, EU

^a erminald.bertel@uibk.ac.at

Received: 21 July 2010
Accepted: 11 October 2010

Abstract

Variable-temperature scanning tunnelling microscopy is used to study an order-order phase transition in a virtually defect-free quasi–one-dimensional surface system. The phase transition is driven by competing electronic interactions. The phase diagram is captured by a modified Landau formalism containing a coupling term between two different subsystems. The extra term has the effect of a spontaneously generated field which drives the phase transition. The proposed formalism applies to a variety of problems, where competing interactions produce sometimes counter-intuitive ordering phenomena.