Energy gaps, topological insulator state and zero-field quantum Hall effect in graphene by strain engineering - Condensed Matter > Mesoscale and Nanoscale PhysicsReportar como inadecuado




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Abstract: Among many remarkable qualities of graphene, its electronic propertiesattract particular interest due to a massless chiral character of chargecarriers, which leads to such unusual phenomena as metallic conductivity in thelimit of no carriers and the half-integer quantum Hall effect QHE observableeven at room temperature 1-3. Because graphene is only one atom thick, it isalso amenable to external influences including mechanical deformation. Thelatter offers a tempting prospect of controlling graphene-s properties bystrain and, recently, several reports have examined graphene under uniaxialdeformation 4-8. Although the strain can induce additional Raman features7,8, no significant changes in graphene-s band structure have been eitherobserved or expected for realistic strains of approx. 10% 9-11. Here we showthat a designed strain aligned along three main crystallographic directionsinduces strong gauge fields 12-14 that effectively act as a uniform magneticfield exceeding 10 T. For a finite doping, the quantizing field results in aninsulating bulk and a pair of countercirculating edge states, similar to thecase of a topological insulator 15-20. We suggest realistic ways of creatingthis quantum state and observing the pseudo-magnetic QHE. We also show thatstrained superlattices can be used to open significant energy gaps ingraphene-s electronic spectrum.



Autor: F. Guinea, M. I. Katsnelson, A. K. Geim

Fuente: https://arxiv.org/



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