Dresden 2020 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 15: Graphene (jointly with DY, MA, HL, DS, O) (joint session TT/DY/HL)

HL 15.3: Vortrag

Montag, 16. März 2020, 15:30–15:45, HSZ 201

Virtual experiments on negative refraction across graphene pn junctions — •Wun-Hao Kang and Ming-Hao Liu — Department of Physics, National Cheng Kung University, Tainan, Taiwan

Graphene is a promising 2D material exhibiting optics-like properties due to its relativistic electronic structure linear in momentum. When charge carriers pass through a bipolar junction, the group velocity component parallel to the interface changes sign, leading to a negative refraction angle and hence effectively a negative refraction index in Snell’s law. Many groups have been working on negative refraction in graphene, both theoretically and experimentally. However, most studies focus on the design of Veselago lensing. Here, we revisit a recent experiment [1] and perform quantum transport simulations for the same device geometry, based on the scalable tight-binding model [2]. Under ideal conditions, our result shows clear conductance peaks due to electron focusing, which is a combined effect of Klein tunneling and negative refraction. To single out the effect of negative refraction, we have further proposed a simpler design for future experiments.

[1] G.-H. Lee et al., Nat. Phys. 11, 925–929 (2015)

[2] M.-H. Liu et al., Phys. Rev. Lett. 114, 036601 (2015)