Abstrakt
A2Ir2O7 iridates, where A is a rare earth, crystalize in the ordered pyrochlore structure (space group Fd-3m) for all rare-earth analogues. Both A3+ and Ir4+ ions form sublattices of corner-sharing tetrahedra and are surrounded by 8- and 6- coordinate oxygen cages, respectively.
Many complex (ground) states, e.g., spin ice, spin liquid, or fragmented states stemming from the resulting geometrical frustration have been observed and attracted considerable attention [1]. At higher temperatures, the iridium sublattice tends to order in the so-called all-in-all-out (AIAO) magnetic structure [2] for most analogues, influencing the magnetic moments on the A sublattice at lower temperatures.
A strong spin-orbit coupling tied with the Ir4+ ions was predicted to lead to topological phases such as Weyl semimetal or topological Mott insulator [3,4]. We present a study of electrical transport and magnetic properties of heavy-rare-earth A2Ir2O7 iridates (A=Dy-Lu) synthesized employing the CsCl flux method.
A broad anomaly in the electrical resistivity data connected with the semiconductor-insulator transition is scanned and discussed in comparison to the AIAO ordering of the Ir sublattice [5]. The study is complimented by magnetoresistance measurements and previous magnetic and specific heat results on the same samples.
A comprehensive picture is drawn for this understudied part of the rare-earth A2Ir2O7 series in respect to the connected electrical transport and magnetic properties. [1] E. Lefrançois et al., Nat.
Commun. 8, 209 (2017). [2] H. Jacobsen et al., Phys.
Rev. B 101, 104404 (2020). [3] W.
Witczak-Krempa et al., Annu. Rev.
Condens. Matter Phys. 5, 57-82 (2014). [4] X.
Wan et al., Phys. Rev.
B 83, 205101 (2011). [5] K. Matsuhira et al., J.
Phys. Soc.
Jpn. 80, 094701 (2011).