NCTS (South)


DATE2015-02-26

TIME14:10

PLACE物理二館地下室 (49X04)

FIELDOther

SPEAKER 劉明豪 - Institute of Theoretical Physics, University of Regensburg, Germany

TITLEQuantum transport simulation for ballistic graphene devices

ABSTRACTGraphene, a truly two-dimensional material discovered in 2004, is known to be an ideal platform for testing and studying relativistic quantum mechanics for its unique linear-in-momentum energy band structure. However, many of the predicted intriguing phenomena based on the Dirac model were hidden in previous experiments due to limited sample quality. In 2013, micron-scale phase-coherent lengths in graphene have been experimentally achieved, and real-space quantum transport simulations that take into account the device geometry have since then become a powerful supporting tool for high-quality graphene transport experiments [1]. In this talk, basic theoretical elements for modelling and simulating real graphene devices will be briefly introduced [2]. Concrete examples will be subsequently illustrated, including suspended graphene pn junctions [2], graphene on substrate with multiple fine topgates [3], and hBN-encapsulated bilayer graphene pnp junctions [4], all of which show very good agreement between experiments and my simulations. Fruitful physics covered in these experiments such as Klein and anti-Klein tunneling, Fabry-Perot interference, half-integer quantum Hall effect, and snake states, will be discussed. The talk will be closed by a summary followed by an outlook for current and future research directions.

[1] P. Rickhaus, R. Maurand, M.-H. Liu et al., Nat. Commun. 4, 2342 (2013).
[2] M.-H. Liu, P. Rickhaus, P. Makk et al., Phys. Rev. Lett. 114, 036601 (2015).
[3] M. Drienovsky, F.-X. Schrettenbrunner, A. Sandner et al., Phys. Rev. B 89, 115421 (2014).
[4] A. Varlet, M.-H. Liu, V. Krueckl et al., Phys. Rev. Lett. 113, 116601 (2014).