37 citations · 195 across the 17 of their papers we have counts for
11 papers · 1 filter
Quantum Phase diagrams and transitions for Chern topological insulators
Ralph M. Kaufmann, Mohamad Mousa, Birgit Wehefritz-Kaufmann
Topological invariants such as Chern classes are by now a standard way to classify topological phases. Introducing and varying parameters in such systems leads to phase diagrams, w…
Local models and global constraints for degeneracies and band crossings
Ralph M. Kaufmann, Sergei Khlebnikov, Birgit Wehefritz-Kaufmann
We study topological properties of families of Hamiltonians which may contain degenerate energy levels aka. band crossings. The primary tool are Chern classes, Berry phases and sli…
Noncommutative topological invariant
Ralph M. Kaufmann, Dan Li, Birgit Wehefritz-Kaufmann
We generalize the invariant of topological insulators using noncommutative differential geometry in two different ways. First, we model Majorana zero modes by KQ-cyc…
The Stiefel--Whitney theory of topological insulators
Ralph M. Kaufmann, Dan Li, Birgit Wehefritz-Kaufmann
We study the topological band theory of time reversal invariant topological insulators and interpret the topological invariant as an obstruction in terms of Stiefel-…
Topological insulators and K-theory
Ralph M. Kaufmann, Dan Li, Birgit Wehefritz-Kaufmann
We analyze the topological invariant, which characterizes time reversal invariant topological insulators, in the framework of index theory and K-theory. The topologi…
Notes on topological insulators
Ralph M. Kaufmann, Dan Li, Birgit Wehefritz-Kaufmann
This paper is a survey of the -valued invariant of topological insulators used in condensed matter physics. The -valued topological invariant, which was o…