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TT: Fachverband Tiefe Temperaturen
TT 77: Frustrated Magnets: Strong Spin-Orbit Coupling II
TT 77.5: Vortrag
Donnerstag, 21. März 2024, 16:00–16:15, H 3025
Band structure study of the magnetic ground state of pyrochlore iridates — •Alexander Yaresko, Aleksandra Krajewska, Tomohiro Takayama, and Hidenori Takagi — Max Plank Institute for Solid State Research, Stuttgart, Germany
Most of pyrochlore R2Ir2O7 iridates, where R3+ is a rare-earth ion, undergo a transition to non-collinear magnetically ordered state with Ir moments pointing either to or from the center of a tetrahedron. This all-in-all-out (AIAO) order is thought to be stabilized by strong Dzyaloshinskii-Moriya interaction (DMI) allowed on the pyrochlore lattice. Recently, a new In2Ir2O7 iridate was synthesized in which the trigonal distortion and Ir-O-Ir bond bending is even stronger than in Lu2Ir2O7. Thus, one would expect that also in this compound strong DMI stabilizes AIAO order.
In order to verify this we performed LDA+U calculations for In2Ir2O7 and R2Ir2O7 (R=Y, Lu, Nd) with different non-collinear magnetic structures. For R2Ir2O7, in agreement with neutron diffraction data the lowest energy was obtained for AIAO order. For In2Ir2O7, however, non-collinear coplanar Palmer-Chalker order is found to be the most favorable one. This prediction is supported by recent neutron diffraction experiments. Comparison of exchange parameters estimated from the calculations suggests that the change of the magnetic ground state in In2Ir2O7 may be caused by competition between DMI and local easy plane anisotropy which becomes allowed because of strong trigonal splitting of Ir d t2g states.
Keywords: Dzyaloshinskii-Moriya interaction; all-in-all-out order; pyrochlore lattice; band structure calculations