Speaker: Xiao HU 胡 暁

 International Center for Materials Nanoarchitectonics (WPI-MANA)

 National Institute for Materials Science (NIMS), Tsukuba, Japan

Abstract:

Honeycomb lattice has played an important role in the course of fostering topology physics as known from the Haldane model and the Kane-Mele model [1]. Recently, we proposed a new way to derive nontrivial topology based on honeycomb structure with time-reversal symmetry. The first example is to achieve a topological photonic crystal made of dielectric materials such as silicon [2]. We identify a pseudospin degree of freedom in electromagnetic (EM) modes associated with C6v crystalline symmetry, and show that nontrivial topology is induced by photonic p-d band inversion. Recent microwave experiments confirm our theory [3,4]. The idea can be extended to phononic systems, physical waves, and electronic systems. We investigate graphene with detuned nearest-neighbor hopping energy or nano-hole arrays, and find in the latter case topological edge/interface states protected by energy gap over 1eV [5,6,7]. Recent progresses and perspectives of the present approach will be discussed.

References:

[1] H.-M. Weng, R. Yu, X. Hu, X. Dai and Z. Fang, Adv. Phys. 64, 227 (2015).

[2] L.-H. Wu and X. Hu, Phys. Rev. Lett. 114, 223901 (2015).

[3] Y.-T. Yang, X. Hu and Z.-H. Hang, Phys. Rev. Lett. 120, 217401 (2018).

[4] Y. Li, H. Chen and X. Hu, arXiv:1801.04395.

[5] L.-H. Wu and X. Hu, Sci. Rep. 6, 24347 (2016).

[6] T. Kariyado and X. Hu, Sci. Rep. 7, 16515 (2017).

[7] T. Kariyado, Y.-C. Jiang, H.-X. Yang and X. Hu, arXiv:1801.03115.

Time & Date: 15:00pm, June 13 (Wedn.), 2018

Venue: Rm. N306, UCAS Teaching Building [View Map]