Tuning Topologically Nontrivial States in the BHT-Ni Metal-Organic Framework

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Chemistry

Background:

• Metal-organic frameworks (MOFs) offer tunable electronic properties.
• Quantum Hall effects are crucial in condensed matter physics.
• BHT-Ni is an experimentally accessible MOF with potential for novel electronic states.

Purpose of the Study:

• To demonstrate the creation of multiple quantum states in BHT-Ni.
• To investigate the effects of electron doping on quantum state formation.
• To explore the role of geometrical symmetry breaking on these states.

Main Methods:

• First-principles calculations were employed.
• Density Functional Theory (DFT) was used to model electronic structures.
• Analysis of band gaps, Fermi energy shifts, and conductivity was performed.

Main Results:

• Quantum spin Hall state induced by two-electron doping, showing quantized spin Hall conductivity.
• Quantum anomalous Hall state induced by four-electron doping, exhibiting quantized anomalous Hall conductivity.
• Centrosymmetric structures preserve the quantum spin Hall state, while noncentrosymmetric structures exhibit the valley Hall effect.

Conclusions:

• BHT-Ni is a promising material for hosting multiple quantum states.
• Electron doping is an effective strategy to control quantum phenomena in MOFs.
• Geometrical symmetry plays a critical role in determining the type and preservation of quantum states and their associated conductivities.