Even-integer Quantum Hall Effect in an Oxide Caused by Hidden Rashba Effect

Abstract

In the presence of high magnetic field, quantum Hall systems usually host both even- and odd-integer quantized states because of lifted band degeneracies. Selective control of these quantized states is challenging but essential to understand the exotic ground states and manipulate the spin textures. Here, we study the quantum Hall effect in Bi2O2Se thin films. In magnetic fields as high as 50 T, we observe only even-integer quantum Hall states, but no sign of odd-integer states. However, when reducing the thickness of the epitaxial Bi2O2Se film to one unit cell, we observe both odd- and even-integer states in this Janus (asymmetric) film grown on SrTiO3. By means of a Rashba bilayer model based on ab initio band structures of Bi2O2Se thin films, we can ascribe the absence of odd-integer states in thicker films to the hidden Rasbha effect, where the local inversion symmetry breaking in two sectors of the [Bi2O2]2+ layer yields opposite Rashba spin polarizations, which compensate with each other. In the one unit cell Bi2O2Se film grown on SrTiO3, the asymmetry introduced by top surface and bottom interface induces a net polar field. The resulting global Rashba effect lifts the band degeneracies present in the symmetric case of thicker films.

6 Figures, 23 pages

References in corpus (7)

• Dissipationless Quantum Spin Current at Room Temperature
• High Electron Mobility, Quantum Hall Effect and Anomalous Optical Response in Atomically Thin InSe
• Engineering symmetry breaking in two-dimensional layered materials
• Large Bychkov-Rashba spin-orbit coupling in high-mobility GaN/AlGaN heterostructures
• Large modulation of the Shubnikov-de Haas oscillations by the Rashba interaction at the LaAlO${}_3$/SrTiO${}_3$ interface
• Odd-integer quantum Hall states and giant spin susceptibility in p-type few-layer WSe2
• Layer- and Gate-tunable Spin-Orbit Coupling in a High Mobility Few-Layer Semiconductor

Cited by in corpus (2)

• Dirac-Rashba fermions and quantum valley Hall insulators in graphene-based 2D heterostructures
• Engineering stacking-induced topological phase transitions in bilayer heterostructures