title: Strongly frustrated triangular spin lattice emerging from triplet dimer formation in honeycomb Li2IrO3.
abstract: Iridium oxides with a honeycomb lattice have been identified as platforms for the much anticipated Kitaev topological spin liquid: the spin-orbit entangled states of Ir(4+) in principle generate precisely the required type of anisotropic exchange. However, other magnetic couplings can drive the system away from the spin-liquid phase. With this in mind, here we disentangle the different magnetic interactions in Li2IrO3, a honeycomb iridate with two crystallographically inequivalent sets of adjacent Ir sites. Our ab initio many-body calculations show that, while both Heisenberg and Kitaev nearest-neighbour couplings are present, on one set of Ir-Ir bonds the former dominates, resulting in the formation of spin-triplet dimers. The triplet dimers frame a strongly frustrated triangular lattice and by exact cluster diagonalization we show that they remain protected in a wide region of the phase diagram.
authors.affiliation: Institute for Theoretical Solid State Physics, IFW Dresden, Helmholtzstrasse 20, 01069 Dresden, Germany.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nishimoto
authors.affiliation: Institute for Theoretical Solid State Physics, IFW Dresden, Helmholtzstrasse 20, 01069 Dresden, Germany.
authors.forename: Vamshi M
authors.initials: VM
authors.lastname: Katukuri
authors.affiliation: Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Russia.|Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Street 38, 01187 Dresden, Germany.
authors.forename: Viktor
authors.initials: V
authors.lastname: Yushankhai
authors.affiliation: Institute for Theoretical Chemistry, Universität Stuttgart, Pfaffenwaldring 55, 70550 Stuttgart, Germany.
authors.forename: Hermann
authors.initials: H
authors.lastname: Stoll
authors.affiliation: Institute for Theoretical Solid State Physics, IFW Dresden, Helmholtzstrasse 20, 01069 Dresden, Germany.
authors.forename: Ulrich K
authors.initials: UK
authors.lastname: Rößler
authors.affiliation: Institute for Theoretical Solid State Physics, IFW Dresden, Helmholtzstrasse 20, 01069 Dresden, Germany.
authors.forename: Liviu
authors.initials: L
authors.lastname: Hozoi
authors.affiliation: Institute for Theoretical Solid State Physics, IFW Dresden, Helmholtzstrasse 20, 01069 Dresden, Germany.|Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Street 38, 01187 Dresden, Germany.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Rousochatzakis
authors.affiliation: Institute for Theoretical Solid State Physics, IFW Dresden, Helmholtzstrasse 20, 01069 Dresden, Germany.|Department of Physics, Technical University Dresden, Helmholtzstrasse 10, 01069 Dresden, Germany.
authors.forename: Jeroen
authors.initials: J
authors.lastname: van den Brink