1. Klein Tunneling and Dirac Physics in Graphene
Xinyuan Lai
P502 Presentation/Spring 2018

2. P502 Presentation/Spring 2018
Overview
Klein Tunneling with Massless Dirac Fermion in Graphene:
Tunneling Through a Barrier
Whispering Gallery Modes (WGM) in Graphene
Berry Phase within the Pusedospin Picture:
On/off Berry Phase Switch in a WGM Cavity
P502 Presentation/Spring 2018

3. P502 Presentation/Spring 2018
1. The Klein Paradox ?
T = 1 ?
The Klein Paradox for infinite high barrier as
P502 Presentation/Spring 2018

4. P502 Presentation/Spring 2018
Mono-Layer Graphene
over
γ0 and a are the intralayer nearest neighbor hopping
energy and distance
P502 Presentation/Spring 2018

5. Klein Tunneling with Massless Dirac Fermion
Where: B
P502 Presentation/Spring 2018

6. P502 Presentation/Spring 2018
Transmittance Profile and Klein Tunneling in graphene through npn-Juction
The Transmittance is 1 at some certain “magic angle”
Half-Period Phase Shift from Berry Phase with magnetic field Applied
P502 Presentation/Spring 2018

7. Whispering Gallery Modes (WGM) in Graphene
P502 Presentation/Spring 2018

8. 2. Berry Phase with Pseudospin Precession
Replace by
Solely Depends on φ
P502 Presentation/Spring 2018

9. On/off Berry Phase Switch in Graphene WGM Cavity
Landau Level Splitting
P502 Presentation/Spring 2018

10. P502 Presentation/Spring 2018
Conclusion
The Klein Tunneling in Graphene offers a playground for the optics with Massless Dirac Fermions The 2D nature graphene further increase the parameter space of the experiment by offering easy tunable tunneling barrier and electron orbits
P502 Presentation/Spring 2018

11. P502 Presentation/Spring 2018
Reference
[1] F. Ghahari, Science, 2017 [2] Y. Zhao, Science, 2015 [3] M. I. Katsnelson, Nat. Phys., 2006 [4] T. Tudorovskiy, Phys. Scr., 2012 [5] A. Varlet, RRL, 2015 [6] P. Allain, arxiv v3 [7] D. Xiao, Rev. Mod. Phys., 2009 [8] AF Young, Nat. Phys., 2008 [9] A. V. Shytov, PRL, 2008
P502 Presentation/Spring 2018

12. WGM vs. Angular Momentum
P502 Presentation/Spring 2018

13. P502 Presentation/Spring 2018