arXiv subjects

Friedemann Aust

Publications and source records attributed to Friedemann Aust.

2 recordsLinked to original sources

arXiv2021

Magnetic phases for two $t_{2g}$ holes with spin-orbit coupling and crystal field

We investigate two holes in the the $t_{2g}$ levels of a square-lattice Mott insulator with strong spin-orbit coupling. Exact diagonalization of a spin-orbital model valid at strong onsite interactions, but arbitrary spin-orbit coupling and crystal field is complemented by an effective triplon model (valid for strong spin-orbit coupling) and by a semiclassical variant of the model. We provide the magnetic phase diagram depending on crystal field and spin-orbit coupling, which largely agrees for the semiclassical and quantum models, as well as excitation spectra characterizing the various phases.

cond-mat.str-el↗

arXiv2019

Nontrivial Triplon Topology and Triplon Liquid in Kitaev-Heisenberg-type Excitonic Magnets

The combination of strong spin-orbit coupling and correlations, e.g. in ruthenates and iridates, has been proposed as a means to realize quantum materials with nontrivial topological properties. We discuss here Mott insulators where onsite spin-orbit coupling favors a local $J_{\textrm{tot}}=0$ singlet ground state. We investigate excitations into a low-lying triplet, triplons, and find them to acquire nontrivial band topology in a magnetic field. We also comment on magnetic states resulting from triplon condensation, where we find, in addition to the same ordered phases known from the $J_{\textrm{tot}}=\tfrac{1}{2}$ Kitaev-Heisenberg model, a triplon liquid taking the parameter space of Kitaev's spin liquid.

cond-mat.str-el↗