Berlin 2018 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 72: Poster Session: Correlated Electrons

TT 72.54: Poster

Wednesday, March 14, 2018, 15:00–19:00, Poster B

Disorder and Correlations in 3D Kitaev Models — •Kevin O'Brien¹, Maria Hermanns², and Simon Trebst¹ — ¹Institute for Theoretical Physics, University of Cologne, 50937 Cologne, Germany — ²Department of Physics, University of Gothenburg, SE 412 96 Gothenburg, Sweden

Kitaev's honeycomb model is an example of an exactly solvable interacting spin-1/2 model with exchange frustration, providing theorists with the rare opportunity to study the physics of spin fractionalization in its quantum spin liquid groundstate with full analytical control. In their groundstate, the spin-1/2 moments fractionalize into a static, gapped Z2 gauge field as well as into fermionic excitations which may be gapped or gapless. The nature of the gapless phase depends both on the dimension of the underlying lattice and on the projective nature of certain discrete symmetries. The resulting nodal structure of the fermionic excitations ranges from nodal lines to Dirac nodes in 2D and from full Fermi surfaces to nodal lines and even Dirac/Weyl nodes in 3D. While spin-spin correlations in the Kitaev model are short-ranged in general, there are certain long-ranged four-spin correlations which are sensitive to the nodal structure of the fermionic excitations. In this work we investigate the nature in which these correlation functions are determined by the gapless fermionic excitations. Additionally, we examine the role which disordering of the Z2 gauge field plays in altering these correlations. Finally, we explore the connection between the gauge-disordered Kitaev spin liquid and finite temperature calculations.