Scientists / Open questions

Allan H. MacDonald

Quantum Hall effect; two-dimensional electron systems

12 questions

Completing the microscopic theory of the charge-neutrality band gap of nearly aligned graphene on hexagonal boron nitride: relaxation geometry, substrate thickness, and many-body enhancement
Beyond-mean-field theory of the correlated insulator states in magic-angle twisted bilayer graphene: fluctuation corrections, parameter and screening control, metastability, and the Chern-number criterion
Establishing the Majorana nature of the zero-bias end states of ferromagnetic atomic chains on superconductors: high-resolution, momentum-resolved, and topological-discrimination tests, and manipulation toward braiding
Quantitative experimental realization of the predicted intrinsic anomalous Hall effect in single-phase noncollinear antiferromagnetic Mn3Ir
Microscopic mechanism of superconductivity and the correlated-state phase diagram of magic-angle twisted bilayer graphene
Quantitative theory of the magnetic (time-reversal-odd) spin Hall and magnetic inverse spin Hall effects in magnetic crystals: extrinsic and disorder-dependent contributions beyond the relaxation-time approximation, the unexplained spin-pumping voltage jump in Mn3Sn, and systematic materials mapping
Exchange, sigma-orbital, and interaction corrections to the screening and small-energy-scale band structure of ABC-stacked graphene trilayers
Determining the proximity-induced spin–orbit parameters, spin-relaxation mechanisms, and topological ground state of monolayer graphene on WS2
A full quantitative theory of superconductivity in magic-angle twisted bilayer graphene: Coulomb screening, particle–hole asymmetry, and pairing treated on equal footing
Asymptotic zero-temperature conductivity at the Dirac point of disordered graphene: mechanism, value, and symplectic-scaling versus electron-hole-puddle percolation
Quantitative theory and sub-nanometre probes of the electrical double layer at few-layer graphene–ionic-liquid interfaces: correlated electrode–ion response and the layer-dependent capacitance anomaly
Quantitative first-principles account of the anomalous Hall conductivity of ferromagnetic bcc Fe: exchange-correlation fidelity, disorder-induced extrinsic terms, and the theory-experiment discrepancy

Back to open problems

Completing the microscopic theory of the charge-neutrality band gap of nearly aligned graphene on hexagonal boron nitride: relaxation geometry, substrate thickness, and many-body enhancement

Beyond-mean-field theory of the correlated insulator states in magic-angle twisted bilayer graphene: fluctuation corrections, parameter and screening control, metastability, and the Chern-number criterion

Establishing the Majorana nature of the zero-bias end states of ferromagnetic atomic chains on superconductors: high-resolution, momentum-resolved, and topological-discrimination tests, and manipulation toward braiding

Quantitative experimental realization of the predicted intrinsic anomalous Hall effect in single-phase noncollinear antiferromagnetic Mn3Ir

Microscopic mechanism of superconductivity and the correlated-state phase diagram of magic-angle twisted bilayer graphene

Exchange, sigma-orbital, and interaction corrections to the screening and small-energy-scale band structure of ABC-stacked graphene trilayers

Determining the proximity-induced spin–orbit parameters, spin-relaxation mechanisms, and topological ground state of monolayer graphene on WS2

A full quantitative theory of superconductivity in magic-angle twisted bilayer graphene: Coulomb screening, particle–hole asymmetry, and pairing treated on equal footing

Asymptotic zero-temperature conductivity at the Dirac point of disordered graphene: mechanism, value, and symplectic-scaling versus electron-hole-puddle percolation

Quantitative theory and sub-nanometre probes of the electrical double layer at few-layer graphene–ionic-liquid interfaces: correlated electrode–ion response and the layer-dependent capacitance anomaly

Quantitative first-principles account of the anomalous Hall conductivity of ferromagnetic bcc Fe: exchange-correlation fidelity, disorder-induced extrinsic terms, and the theory-experiment discrepancy