Posted by Kenneth Burch
On September - 24 - 2015
Comments Off on Sum-Rule Constraints on the Surface State Conductance of Topological Insulators
We report the Drude oscillator strength D and the magnitude of the bulk band gap Eg of the epitaxially grown, topological insulator (Bi,Sb)2Te3. The magnitude of Eg, in conjunction with the model independent f-sum rule, allows us to establish an upper bound for the magnitude of D expected in a typical Dirac-like system composed of linear bands. The experimentally observed D is found to be at or below this theoretical upper bound, demonstrating the effectiveness of alloying in eliminating bulk charge carriers. Moreover, direct comparison of the measured D to magnetoresistance measurements of the same sample supports assignment of the [ Read More ]
Posted by Kenneth Burch
On April - 7 - 2015
Comments Off on Scattering Continuum and Possible Fractionalized Excitations in RuCl3
The combination of electronic correlation and spin-orbit coupling is thought to precipitate a variety of highly unusual electronic phases in solids, including topological and quantum spin liquid states. We report a Raman scattering study that provides evidence for unconventional excitations in α−RuCl3, a spin-orbit coupled Mott insulator on the honeycomb lattice. In particular, our measurements reveal unusual magnetic scattering, typified by a broad continuum. The temperature dependence of this continuum is evident over a large scale compared to the magnetic ordering temperature, suggestive of frustrated magnetic interactions. This is confirmed through an analysis of the phonon linewidths, which show a related [ Read More ]