Jeudi 01 novembre 2012 à 10h15
Salle 234, Ecole de Physique

Density waves instability and a skyrmion lattice on the surface of strong topological insulators

Yuval Baum, Weizmann Institute of Science

The gapless surface states of strong topological insulators have drawn a great deal of attention over the past few years. In a previous work [1] it was shown that for a strong enough electron-electron interaction the surface of a strong topological insulator is unstable to the formation of spontaneous uniform magnetization. In this work [2] we analyzed the instability conditions for spin-density- waves (SDW) formation on the surface of strong topological insulators. We find that for a certain range of energies the SDW instability is favored compared to the uniform one. We also find that the SDW are of spiral nature and for a certain range of parameters a Skyrmion-lattice is formed on the surface. We show that this phase may have a non trivial Chern-number even in the absence of an external magnetic field. Finally, we claim that a controlled network of one-dimensional chiral channels can be established on the surface of a strong topological insulator. [1] Y. Baum and A. Stern, Phys. Rev. B 85, 121105(R) (2012) [2] Y. Baum and A. Stern, cond-mat/1208.2576v1 (2012)