Towards Topological States in Silver Bismuthates Synthesized under High-Pressure

The stoichiometric silver bismuthate Ag₂BiO₃ typically contains equal amounts of bismuth in the Bi⁺³ and Bi⁺⁵ states, and this charge ordering renders Ag₂BiO₃ insulating [1]. Recent theoretical predictions of metal-insulator transition and Weyl semimetal state in Ag₂BiO₃ have revived the interest in this material [2]. However, such novel properties are only expected in the absence of the charge ordering of bismuth. Here, we examine the possibility of achieving a topologically nontrivial phase and suppressing the charge ordering in Ag₂BiO₃ via chemical substitution/doping. We present a new high-pressure synthesis route for Ag₂BiO₃, which we utilize for substituting/doping at the Ag site. Also, we explore the possibility of making Ag-deficient Ag_2-xBiO₃ phases using high pressure synthesis. In the presentation, we will discuss the specific synthesis conditions, Rietveld refinement, and some magnetic and transport properties in detail.

[1] C. B. M. Oberndorfer et al., Solid State Sciences 8, 267 (2006).
[2] J. He et al., Nature Communications 9, 492 (2018).