Hole dynamics in exactly solvable gapped and gapless spin liquids

Rövid cím: 
Hole dynamics in exactly solvable spin liquids
2016. 05. 20. 10:15
BME Fizikai Intézet, Elméleti Fizika Tanszék, Budafoki út 8. F-épület, III lépcsőház, szemináriumi szoba
Gábor Halász (Oxford Univ.)

We present a controlled microscopic study of hole dynamics in both a gapped and a gapless spin liquid. Our approach is complementary to previous phenomenological works as we introduce mobile holes into the spin liquid ground state of the exactly solvable Kitaev honeycomb model. In the gapped phase of the model, we address the single-particle properties of individual holes (such as their particle statistics and hopping properties) and the multi-particle ground state at a finite density of holes. Our main result is that the holes possess internal degrees of freedom as they can bind the fractional excitations of the spin liquid and that the resulting composite holes with different excitations bound are distinct fractional particles with fundamentally different single-particle properties and different experimental signatures in the multi-particle ground state. In the gapless phase of the model, we consider a single hole and address the possibility of a coherent quasiparticle description by investigating its spectral function. We employ a variational treatment and also study a simplified one-dimensional problem to argue that a mobile hole has a finite quasiparticle weight which vanishes in the stationary limit.