Dresden 2014 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 71: Transport: Majorana Fermions (organized by TT)

TT 71.10: Vortrag

Mittwoch, 2. April 2014, 17:45–18:00, HSZ 03

Quantum spin liquid with a Majorana Fermi surface on the three-dimensional hyperoctagon lattice — •Maria Hermanns and Simon Trebst — Institut für Theoretische Physik, Universität zu Köln

Motivated by the recent synthesis of β-Li₂IrO₃ – a spin-orbit entangled j=1/2 Mott insulator with a three-dimensional lattice structure of the Ir⁴⁺ ions – we consider generalizations of the Kitaev model, believed to capture some of the microscopic interactions between the Iridium moments, on various trivalent lattice structures in three spatial dimensions. Of particular interest is the so-called hyperoctagon lattice – a cubic non-Bravais lattice, which is probably best described as the premedial lattice of the hyperkagome lattice – for which the ground state is a gapless quantum spin liquid where the gapless Majorana modes form an extended Majorana Fermi surface. We demonstrate that this Majorana Fermi surface is inherently protected by lattice symmetries and discuss possible instabilities when allowing for a reduction in lattice symmetries. We discuss these findings also in light of recent results obtained for the hyperhoneycomb lattice.