The quantum Hall effect (QHE), and devices reliant on it, will continue to serve as the foundation of the ohm while also expanding its territory into other SI derived units. The foundation, evolution, and significance of all of these devices exhibiting some form of the QHE will be described in the context of optimizing future electrical resistance standards. As the world adapts to using the quantum SI, it remains essential that the global metrology community pushes forth and continues to innovate and produce new technologies for disseminating the ohm and other electrical units.
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http://dx.doi.org/10.1088/1361-6641/ab37d3 | DOI Listing |
Sci Rep
December 2024
Department of Physics, University of Liverpool, Oxford Street, Liverpool, L69 7ZE, UK.
Topological semimetals have recently garnered widespread interest in the quantum materials research community due to their symmetry-protected surface states with dissipationless transport which have potential applications in next-generation low-power electronic devices. One such material, [Formula: see text], exhibits Dirac nodal arcs and although the topological properties of single crystals have been investigated, there have been no reports in crystalline thin film geometry. We examined the growth of [Formula: see text] heterostructures on a range of single crystals by optimizing the electron beam evaporation of Pt and Sn and studied the effect of vacuum thermal annealing on phase and crystallinity.
View Article and Find Full Text PDFJ Phys Condens Matter
December 2024
Departamento de Física, Facultad de Ciencias, Universidad Nacional Autónoma de México, Circuito interior s/n, Colonia Universidad Nacional Autónoma de México, Coyoacán, C.P. 0451 Ciudad Universitaria, Ciudad de México, México, Ciudad de Mexico, 04510, MEXICO.
Magnetic fields can be introduced into discrete models of quantum systems by the Peierls substitution. For tight-binding Hamiltonians, the substitution results in a set of (Peierls) phases that are usually calculated from the magnetic vector potential. As the potential is not unique, a convenient gauge can be chosen to fit the geometry and simplify calculations.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
New Cornerstone Science Laboratory, Department of Physics, University of Hong Kong, Hong Kong, China.
The ability to generate Landau levels using a pseudomagnetic field (PMF), also called an artificial gauge field, opens up new pathways for exploring fundamental physics and developing novel applications based on topological protection. In this Letter, we simultaneously realize a PMF and a pseudoelectric field (PEF) on a photonic crystal platform and observe a rainbow effect of the Landau zeroth modes. While a PMF induces a series of discretized Landau levels of photons in a similar way as the quantum Hall effect for electrons, a PEF breaks the degeneracy of the flat band of Landau levels over a broad range.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA.
The crystallographic restriction theorem constrains two-dimensional nematicity to display either Ising (Z_{2}) or three-state-Potts (Z_{3}) critical behaviors, both of which are dominated by amplitude fluctuations. Here, we use group theory and microscopic modeling to show that this constraint is circumvented in a 30°-twisted hexagonal bilayer due to its emergent quasicrystalline symmetries. We find a critical phase dominated by phase fluctuations of a Z_{6} nematic order parameter and bounded by two Berezinskii-Kosterlitz-Thouless (BKT) transitions, which displays only quasi-long-range nematic order.
View Article and Find Full Text PDFSmall
December 2024
SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon, 16419, Republic of Korea.
Among 2-dimensional (2D) non-layered transition-metal chalcogenides (TMCs), cobalt sulfides are highly interesting because of their diverse structural phases and unique properties. The unique magnetic properties of TMCs have generated significant interest in their potential applications in future spintronic devices. In addition, their high conductivity, large specific surface area, and abundant active sites have attracted attention in the field of catalysis.
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