Stephen R. Power
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View article: Students’ construction of linear and non-linear qualitative graphs corresponding to a hypothetical physics experiment
Students’ construction of linear and non-linear qualitative graphs corresponding to a hypothetical physics experiment Open
We report on a systematic investigation of what first-year university science students (N=755) attend to when asked to draw non-numerical Cartesian graphs pertaining to two hypothetical experimental setups: a ball rolling along a track, an…
View article: Unveiling the Miniband Structure of Graphene Moiré Superlattices via Gate-Dependent Terahertz Photocurrent Spectroscopy
Unveiling the Miniband Structure of Graphene Moiré Superlattices via Gate-Dependent Terahertz Photocurrent Spectroscopy Open
Moiré superlattices formed at the interface between stacked 2D atomic crystals offer limitless opportunities to design materials with widely tunable properties and engineer intriguing quantum phases of matter. However, despite progress, pr…
View article: Tunable Dot Platform for Controlling Electron Flow in Graphene
Tunable Dot Platform for Controlling Electron Flow in Graphene Open
We introduce an innovative graphene-based architecture to control electronic current flows. The tunable dot platform (TDP) consists of an array of gated dots, with independently adjustable potentials, embedded in graphene. Inspired by Mie …
View article: Edge disorder and magnetism in graphene nanoribbons: an inverse modelling approach
Edge disorder and magnetism in graphene nanoribbons: an inverse modelling approach Open
It is difficult to completely eliminate disorder during the fabrication of graphene-based nanodevices. From a simulation perspective, it is straightforward to determine the electronic transport properties of disordered devices if complete …
View article: Edge disorder and magnetism in graphene nanoribbons: an inverse modelling approach
Edge disorder and magnetism in graphene nanoribbons: an inverse modelling approach Open
It is difficult to completely eliminate disorder during the fabrication of graphene-based nanodevices. From a simulation perspective, it is straightforward to determine the electronic transport properties of disordered devices if complete …
View article: Students’ scaling of axes when constructing qualitative graphs that represent a physics scenario
Students’ scaling of axes when constructing qualitative graphs that represent a physics scenario Open
We have studied how first-year university science students construct graphs based on hypothetical qualitative physics scenarios. We gave students a questionnaire that asked them to complete two Cartesian graphs in one of three different sc…
View article: One-dimensional topological channels in heterostrained bilayer graphene
One-dimensional topological channels in heterostrained bilayer graphene Open
The domain walls between AB- and BA-stacked gapped bilayer graphene have garnered intense interest as they host topologically-protected, valley-polarised transport channels. The introduction of a twist angle between the bilayers and the as…
View article: The emergence of interface states in graphene/transition metal dichalcogenides heterostructure with lateral interface
The emergence of interface states in graphene/transition metal dichalcogenides heterostructure with lateral interface Open
The relative strength of different proximity spin-orbit couplings in graphene on transition metal dichalcogenides (TMDC) can be tuned via the metal composition in the TMDC layer. While Gr/MoSe$_2$, has a normal gap, proximity to WSe$_2$ in…
View article: Strain-induced stacking transition in bilayer graphene
Strain-induced stacking transition in bilayer graphene Open
Strain, both naturally occurring and deliberately engineered, can have a considerable effect on the structural and electronic properties of 2D and layered materials. Uniaxial or biaxial heterostrain modifies the stacking arrangement of bil…
View article: Proximity spin-orbit coupling in graphene on alloyed transition metal dichalcogenides
Proximity spin-orbit coupling in graphene on alloyed transition metal dichalcogenides Open
The negligible intrinsic spin-orbit coupling (SOC) in graphene can be enhanced by proximity effects in stacked heterostructures of graphene and transition metal dichalcogenides (TMDCs). The composition of the TMDC layer plays a key role in…
View article: Predicting magnetic edge behaviour in graphene using neural networks
Predicting magnetic edge behaviour in graphene using neural networks Open
Magnetic moments near zigzag edges in graphene allow complex nanostructures with customised spin properties to be realised. However, computational costs restrict theoretical investigations to small or perfectly periodic structures. Here we…
View article: Have mysterious topological valley currents been observed in graphene superlattices?
Have mysterious topological valley currents been observed in graphene superlattices? Open
We provide a critical discussion concerning the claim of topological valley currents, driven by a global Berry curvature and valley Hall effect proposed in recent literature. After pointing out a major inconsistency of the theoretical scen…
View article: Have Mysterious Topological Valley Currents Been Observed in Graphene Superlattices?
Have Mysterious Topological Valley Currents Been Observed in Graphene Superlattices? Open
We provide a critical discussion concerning the claim of topological valley currents, driven by a global Berry curvature and valley Hall effect proposed in recent literature. After pointing out a major inconsistency of the theoretical scen…
View article: Have Mysterious Topological Valley Currents Been Observed in Graphene\n Superlattices?
Have Mysterious Topological Valley Currents Been Observed in Graphene\n Superlattices? Open
We provide a critical discussion concerning the claim of topological valley\ncurrents, driven by a global Berry curvature and valley Hall effect proposed in\nrecent literature. After pointing out a major inconsistency of the theoretical\ns…
View article: Valley current generation using biased bilayer graphene dots
Valley current generation using biased bilayer graphene dots Open
Intrinsic and extrinsic valley Hall effects are predicted to emerge in\ngraphene systems with uniform or spatially-varying mass terms. Extrinsic\nmechanisms, mediated by the valley-dependent scattering of electrons at the\nFermi surface, c…
View article: Valley Hall effect and nonlocal resistance in locally gapped graphene
Valley Hall effect and nonlocal resistance in locally gapped graphene Open
We report on the emergence of bulk, valley-polarized currents in graphene-based devices, driven by spatially varying regions of broken sublattice symmetry, and revealed by nonlocal resistance (RNL) fingerprints. By using a combination of q…
View article: One-dimensional confinement and width-dependent bandgap formation in epitaxial graphene nanoribbons
One-dimensional confinement and width-dependent bandgap formation in epitaxial graphene nanoribbons Open
View article: Nonlocal Spin Dynamics in the Crossover from Diffusive to Ballistic Transport
Nonlocal Spin Dynamics in the Crossover from Diffusive to Ballistic Transport Open
Improved fabrication techniques have enabled the possibility of ballistic transport and unprecedented spin manipulation in ultraclean graphene devices. Spin transport in graphene is typically probed in a nonlocal spin valve and is analyzed…
View article: Topological Valley Currents in Graphene with Local Sublattice Asymmetry
Topological Valley Currents in Graphene with Local Sublattice Asymmetry Open
A broken sublattice symmetry opens a band gap in graphene. Due to Berry curvature effects, it has also been predicted to induce equal and opposite anomalous velocities for electrons in the K and K' valleys. The resulting valley Hall effect…
View article: Gate electrostatics and quantum capacitance in ballistic graphene devices
Gate electrostatics and quantum capacitance in ballistic graphene devices Open
We experimentally investigate the charge induction mechanism across gated, narrow, ballistic graphene devices with different degrees of edge disorder. By using magnetoconductance measurements as the probing technique, we demonstrate that d…
View article: Probing the nanoscale origin of strain and doping in graphene-hBN heterostructures
Probing the nanoscale origin of strain and doping in graphene-hBN heterostructures Open
We use confocal Raman microscopy and a recently proposed vector analysis scheme to investigate the nanoscale origin of strain and carrier concentration in exfoliated graphene-hexagonal boron nitride (hBN) heterostructures on silicon dioxid…
View article: Ballistic tracks in graphene nanoribbons
Ballistic tracks in graphene nanoribbons Open
View article: Conductance quantization suppression in the quantum Hall regime
Conductance quantization suppression in the quantum Hall regime Open
View article: Scale-invariant large nonlocality in polycrystalline graphene
Scale-invariant large nonlocality in polycrystalline graphene Open
View article: 1D ferromagnetic edge contacts to 2D graphene/h-BN heterostructures
1D ferromagnetic edge contacts to 2D graphene/h-BN heterostructures Open
We report the fabrication of one-dimensional (1D) ferromagnetic edge contacts to two-dimensional (2D) graphene/h-BN heterostructures. While aiming to study spin injection/detection with 1D edge contacts, a spurious magnetoresistance signal…
View article: Electron trajectories and magnetotransport in nanopatterned graphene under commensurability conditions
Electron trajectories and magnetotransport in nanopatterned graphene under commensurability conditions Open
Commensurability oscillations in the magnetotransport of periodically\npatterned systems, emerging from the interplay of cyclotron orbit and the\npattern periodicity, are a benchmark of mesoscopic physics in electron gas\nsystems. Exploiti…
View article: Scale-invariant large nonlocality in CVD graphene
Scale-invariant large nonlocality in CVD graphene Open
The observation of large nonlocal resistances near the Dirac point in graphene has been related to a variety of intrinsic Hall effects, in which the spin or valley degrees of freedom are controlled by symmetry breaking mechanisms. In turn,…
View article: Nanostructured graphene for spintronics
Nanostructured graphene for spintronics Open
Altres ajuts: The Center for Nanostructured Graphene (CNG) is sponsored by the Danish National Re- search Foundation, Project DNRF103.
View article: Magnetotransport in ballistic graphene antidot lattices
Magnetotransport in ballistic graphene antidot lattices Open
View article: Graphene Nanobubbles as Valley Filters and Beam Splitters
Graphene Nanobubbles as Valley Filters and Beam Splitters Open
The energy band structure of graphene has two inequivalent valleys at the K and K^{'} points of the Brillouin zone. The possibility to manipulate this valley degree of freedom defines the field of valleytronics, the valley analogue of spin…