Crystal phase control in an YBiO3 thin film by using a Ba BiO3 buffer layer

Topological insulators have a non-trivial band structure, forming gapless surface states when coupled to a normal insulator. Until now, applications are hindered by the competition between the insulating bulk and conducting surface states.
Perovskite oxides offer a good alternative, since topological insulating phases are theoretically predicted with band gaps larger than the thermal excitation energy at room temperature [1].

In YBiO3, a topological insulating phase is predicted for the perovskite crystal structure [2]. However, the fluorite phase is thermodynamically more stable than the perovskite phase. By using a buffer layer, it is possibile to stabilise the perovskite phase in the YBiO3 film.

When the YBiO3 is deposited on top of a BaBiO3 buffer layer, a single oriented perovskite phase with the expected lattice constants is observed. These findings pave a way towards the fabrication of quantum devices for testing the hypothesised topological insulating phase in YBiO3.

[1] Y. Zhang et al., Phys. Chem. Chem. Phys. 18(11), 8205-8211 (2016).
[2] H. Jin et al., Scientic Reports 3, 1651 (2013).