168 research outputs found
Non-trivial topological phases in transition metal rich half-Heusler Oxides
Topological Insulators with gapless surface states and insulating bulk in
non-centrosymmetric cubic systems have been extensively explored following the
discovery of two-dimensional quantum spin hall effect in zincblende HgTe. In
such systems the negative band inversion strength E ( E E 0) governs the robustness of the non-trivial topological
states at ambient conditions. Hence, realizing large negative values of
E has been a guiding motivation of several investigations reported in
literature. Here, we present a material design approach which can be employed
to realize large negative values of E in cubic materials such as
half-Heusler (HH) oxides with 18 valence electron configurations. We explore 27
HH oxides of the form ABO (A = Li, K, Rb; B = Cu, Ag, Au) in -,
-, and -phase (by placing transition metal atom at different
Wyckoff positions) for their non-trivial topological phase. Off these three
phases, we found that, the -phase of nine HH oxides (wherein the
transition metal atoms occupy 4a Wyckoff positions in the crystal structure) is
the most promising with non-trivial topological phase which is governed by the
mass-darwin relativistic effects enhancing E. Whereas the other phases
were found to be either trivial semiconductors or semimetals or metals and most
of them being dynamically unstable. We focus on RbAuO in -phase with
E of 1.29 eV and the effect of strain fields on the topological
surface states of this compound. We conclude that the -phase of HH
oxide presented here can be synthesized experimentally for diverse room
temperature applications in spintronics and nanoelectronics.Comment: 7 pages, 6 figures, 1 tabl
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