2010/04/30 by Bohm‐Jung Yang, Bohm-Jung Yang, Yong Baek Kim · 2 citations
Chemistry · Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Chemistry #Condensed matter physics #Crystal structure #Crystallography #Electron #Ground state #Kondo effect #Kondo insulator #Materials science #Nuclear materials and radiation effects #Physics #Pyrochlore #Quantum mechanics #Tetragonal crystal system #Topological Materials and Phenomena #Topological insulator #Topology (electrical circuits) #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.82.085111
published as Phys. Rev. B 82, 085111 (2010) · 10 pages, 11 figures, 2 tables
arxiv created 2010/05/12 · openalex publication_date 2010/08/16 · arxiv updated 2015/03/13 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
The possible existence of topological insulators in cubic pyrochlore iridates A2Ir2O7 (A=Y or rare-earth elements) is investigated by taking into account the strong spin-orbit coupling and trigonal crystal-field effect. It is found that the trigonal crystal-field effect, which is always present in real systems, may destabilize the topological insulator proposed for the ideal cubic crystal field, leading to a metallic ground state. Thus the trigonal crystal field is an important control parameter for the metal-insulator changeover. We propose that this could be one of the reasons why distinct low-temperature ground states may arise for the pyrochlore iridates with different A-site ions. On the other hand, examining the electron-lattice coupling, we find that softening of the q=0 modes corresponding to trigonal or tetragonal distortions of the Ir pyrochlore lattice leads to the resurrection of the strong topological insulator. Thus, in principle, a finite-temperature transition to a low-temperature topological insulator can occur via structural changes. We also suggest that the application of the external pressure along [111] or its equivalent directions would be the most efficient way of generating strong topological insulators in pyrochlore iridates.