Localization and the Kosterlitz-Thouless Transition in Disordered Graphene

Localization and the Kosterlitz-Thouless transition in disordered graphene.

We investigate disordered graphene with strong long-range impurities. Contrary to the common belief that delocalization should persist in such a system against any disorder, as the system is expected to be equivalent to a disordered two-dimensional Dirac fermionic system, we find that states near the Dirac points are localized for sufficiently strong disorder (therefore inevitable intervalley s...

The Kosterlitz-Thouless Transition

Matter in the universe is organised in a hierarchical structure. At the bottom we have elementary particles: quarks, gluons, electrons etc. At present we don’t know what these particles are made off. But we believe we know that quarks, gluons etc. make up protons, neutrons, etc. These then go together to make atoms, that are the building blocks of molecules. Atoms and molecules gives us gas, li...

The Kosterlitz-Thouless Phase Transition

Inhomogeneous broadening and the Kosterlitz-Thouless transition.

Torsional-oscillator studies of very thin He films have found nonuniversal behavior of the superfluid response as a function of coverage. The temperature width of the superfluid transition region is nonmonotonic in the areal density n and exhibits cusplike variations at half of the layering period. We explore the assumption that this additional broadening is caused by macroscopic inhomogeneitie...

Introduction to the Berezinskii-Kosterlitz-Thouless Transition

This essay examines the Berezinskii-Kosterlitz-Thousless transition in the two-dimensional XY model. It is an imporant example of phase transitions occuring without an ordered phase or symmetry breaking, and introduced topological ideas into the concerns of condensed matter physicists.