The A₂Ir₂O₇ oxides, crystallizing in the pyrochlore structure across the whole rare-earth (A) series, have been an attractive subject for the scientific community for their frequently complex properties. Both A³⁺ and Ir⁴⁺ ions individually reside on interpenetrating sublattices of corner-sharing tetrahedra, hence, forming a 3D geometrically frustrated structure. Frustrated magnetic moments are prevented from ordering down to the lowest temperatures and states such as spin glass, spin ice, spin liquid, or, so-called, fragmented states can be realized [1]. In addition, a strong spin-orbit coupling (SOC) of 5d-electron iridium, together with relatively weak electron correlations between extended 5d-orbitals result in various complex states observed/proposed in these compounds, e.g., topological phases, Weyl semi-metal (WSM) or topological Mott insulator [2].

This presentation summarizes some of the older as well as very recent results tied with the work on the dissertation thesis of Daniel Staško. The results include transport [3], magnetic and structure properties of A₂Ir₂O₇ oxides at ambient and/or high pressure.

[1] E. Lefrançois, V. Cathelin, E. Lhotel, J. Robert, P. Lejay, C.V. Colin, B. Canals, F. Damay, J. Ollivier, B. Fåk, L.C. Chapon, R. Ballou, V. Simonet, Fragmentation in spin ice from magnetic charge injection, Nat. Commun. 8 (2017) 209.
[2] W. Witczak-Krempa, G. Chen, Y.B. Kim, L. Balents, Correlated quantum phenomena in the strong spin-orbit regime, Annu. Rev. Condens. Matter Phys. 5 (2014) 57–82.
[3] D. Staško, K. Vlášová, P. Proschek, M.Klicpera, Conductive properties of heavy-rare-earth A2Ir2O7 iridates synthesized by the CsCl-flux method, J. Phys. Chem. Solids 176 (2023) 111268