Nonlinear optical responses in hydrogenated graphene structures

Abstract

Abstractauthoren We present a theoretical study of the optical spin injection, optical current injection, and second harmonic generation of two 50% hydrogenated graphene structures: C16H8‐alt and C16H8‐up. Optical spin injection, under the incidence of circularly polarized light onto nonmagnetic semiconductors, creates spin‐polarized electrons in the conduction bands. Optical current injection and second‐harmonic generation are nonlinear second‐order effects that are allowed in materials without inversion symmetry. The results are calculated in a full electronic band structure scheme within DFT in the LDA approximation. Our results show an anisotropic behavior in the optical responses of the spin, the current injection, and second harmonic generation. We obtained maximum absolute magnitudes of the degree of spin polarization of 61 and 64% for the alt and up structures, respectively, and it is also possible to optically generate an injection current coming mainly from the carbon layer on both alt and up systems. Besides, we found that both structures are excellent candidates for second harmonic generation.

Pure spin current injection in hydrogenated graphene structures

“…2, has hydrogen alternating on the upper and bottom sides of the carbon sheet. 37 Both the Up and the Alt structures are noncentrosymmetric, and therefore, they are good candidates in which SVI can be induced. In this article, we address theoretically the spin-velocity injection by one-photon absorption of linearly polarized light, analyzing in our structures two possible scenarios of practical interest.…”

Graphene-Boron Nitride 2D Heterosystems Functionalized with Hydrogen: Structure, Vibrations, Optical Response, Electron Band Engineering and Bonding

“…This effect has also been observed experimentally [6,7,8]. Interesting both nonlinear optical response and optical spin injection effects for partially hydrogenated semiconducting graphene have been predicted theoretically [9]. On the other hand, it has also been shown that hydrogenation of outer surfaces of graphene bilayers allows opening the tunable electron gap, which can be prospective in device application [3,10,11].…”

“…We demonstrate the energy dependent spin injections for 50% hydrogenated AA stacked graphene/h-BN bilayer in Fig. 7 (see also [9] for the formalism), leaving more detailed discussion of the linear and nonlinear optical response, its dependence on H dose and the structure specific optical signatures for the forthcoming paper [22]. Fig.…”

“…When performing the simulations for the pristine graphene/b-BN bilayer, van der Waals (vdW) interactions has been also included. Calculation of the optical response and the spin injection has been carried out applying the formalism similar to that one used in [9].…”