We propose a graphene-based full valley- and spin-polarization device based on strained graphene with Rashba spin orbit coupling and magnetic barrier. The underlying mechanism is the coexistence of the valley and single spin band gaps in a certain Fermi energy. By aligning the Fermi energy in the valley and single spin band gaps, remarkable valley- and spin-polarization currents can be accessed.
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http://dx.doi.org/10.1038/srep21590 | DOI Listing |
Nano Lett
December 2024
Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States.
Strain superlattices (SL) in 2D materials like graphene provide an ideal test bed for generating flat bands and exploring the effects of strong correlations. Here we report STM/STS measurements on an engineered SL generated by placing graphene on a periodic array of silica nanospheres. A pseudomagnetic field as high as 55 T is observed along with the formation of pseudo-Landau levels (pLLs), not only at the expected integer values but also at fractional values.
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November 2024
Department of Chemistry, Texas A&M University, College Station, TX 77843, USA.
Using mechanical force to induce chemical reactions with two-dimensional (2D) materials provides an approach for both understanding mechanochemical processes on the molecular level, and a potential method for using mechanical strain as a means of directing the functionalization of 2D materials. To investigate this, we have designed a modular experimental platform which allows for monitoring of reactions on strained graphene Raman spectroscopy as a function of time. Both the strain present in graphene and the corresponding chemical changes it undergoes in the presence of a reagent can be followed concomitantly.
View Article and Find Full Text PDFSci Adv
November 2024
Department of Energy Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea.
Confinement of reactants within nanoscale spaces of low-dimensional materials has been shown to provide reorientation of strained reactants or stabilization of unstable reactants for synthesis of molecules and tuning of chemical reactivity. While few studies have reported chemistry within zero-dimensional pores and one-dimensional nanotubes, organic reactions in confined spaces between two-dimensional materials have yet to be explored. Here, we demonstrate that reactants confined between atomically thin sheets of graphene or hexagonal boron nitride experience pressures as high as 7 gigapascal, which allows the propagation of solvent-free organic reactions that ordinarily do not occur under standard conditions.
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October 2024
School of Physics and Technology, Wuhan University, Wuhan 430072, China.
The generation of pseudo-magnetic fields in strained graphene leads to quantized Landau levels in the absence of an external magnetic field, providing the potential to achieve a zero-magnetic-field analogue of the quantum Hall effect. Here, we report the realization of a pseudo-magnetic field in epitaxial graphene by building a monolayer CrCl/graphene heterointerface. The CrCl crystal structure exhibits spontaneous breaking of three-fold rotational symmetry, yielding an anisotropic displacement field at the interface.
View Article and Find Full Text PDFRep Prog Phys
September 2024
New Cornerstone Science Laboratory, Department of Physics, The University of Hong Kong, Hong Kong, People's Republic of China.
Supersymmetry (SUSY) of a Hamiltonian dictates double degeneracy between a pair of superpartners (SPs) transformed by supercharge, except at zero energy where modes remain unpaired in many cases. Here we explore a SUSY of complete isospectrum between SPs-with paired zero modes-realized by 2D electrons in zero-flux periodic gauge fields, which can describe twisted or periodically strained 2D materials. We find their low-energy sector containing zero (or threshold) modes must be topologically non-trivial, by proving that Chern numbers of the two SPs have a finite difference dictated by the number of zero modes and energy dispersion in their vicinity.
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