3D quantum Hall effect of Fermi arcs in topological semimetals

The quantum Hall effect is usually observed in 2D systems. We show that the Fermi arcs can give rise to a distinctive 3D quantum Hall effect in topological semimetals. Because of the topological constraint, the Fermi arc at a single surface has an open Fermi surface, which cannot host the quantum Hall effect. Via a "wormhole" tunneling assisted by the Weyl nodes, the Fermi arcs at opposite surfaces can form a complete Fermi loop and support the quantum Hall effect. The edge states of the Fermi arcs show a unique 3D distribution, giving an example of (d-2)-dimensional boundary states. This is distinctly different from the surface-state quantum Hall effect from a single surface of topological insulator. As the Fermi energy sweeps through the Weyl nodes, the sheet Hall conductivity evolves from the 1/B dependence to quantized plateaus at the Weyl nodes. This behavior can be realized by tuning gate voltages in a slab of topological semimetal, such as the TaAs family, Cd$_3$As$_2$, or Na$_3$Bi. This work will be instructive not only for searching transport signatures of the Fermi arcs but also for exploring novel electron gases in other topological phases of matter.Comment: 5 pages, 3 figure

Emergence of diverse array of phases in an exactly solvable model

We propose an exactly solvable lattice model, motivated by the significance of the extended Hubbard model ($t-U-V$ model) and inspired by the work of Hatsugai and Kohmoto. The ground state exhibits a diverse array of phases, including the charge-$4e$ condensed phase, the charge-$2e$ superconducting phase, the half-filled insulating phase, the quarter-filled insulating phase, the metallic phase, and an unconventional metallic phase. Among them, the unconventional metallic phase could be of particular significance, for the coexistence of electrons and pairs at zero energy. These findings are poised to advance our understanding and exploration of strongly correlated physics.Comment: 34pages, 15 figure

Poly[bis­(μ-azido-κ2 N 1:N 1)[μ-1,2-bis­(imid­azol-1-yl)ethane-κ2 N 3:N 3′]cadmium]

In the title three-dimensional coordination polymer, [Cd(N3)2(C8H10N4)]n, the coordination geometry around the CdII atom is distorted octa­hedral. The CdII atom is coordinated by two N atoms from two cis-positioned bridging 1,2-bis­(imidazol-1-yl)ethane (bime) ligands and four N atoms from four azide anions. Each azide ligand acts in an end-on bridging coordination mode. The azide ligands and CdII atoms form a one-dimensional zigzag chain constructed from four-membered [Cd(N3)2]n metallacycles extending along the a axis. These inorganic chains are connected with four other chains via bridging bime ligands to form a three-dimensional coordination network

Fluctuation and localization of the nonlinear Hall effect on a disordered lattice

The nonlinear Hall effect has recently attracted significant interest due to its potentials as a promising spectral tool and device applications. A theory of the nonlinear Hall effect on a disordered lattice is a crucial step towards explorations in realistic devices, but has not been addressed. We study the nonlinear Hall response on a lattice, which allows us to introduce disorder numerically and reveal a mechanism that was not discovered in the previous momentum-space theories. In the mechanism, disorder induces an increasing fluctuation of the nonlinear Hall conductance as the Fermi energy moves from the band edges to higher energies. This fluctuation is a surprise, because it is opposite to the disorder-free distribution of the Berry curvature. More importantly, the fluctuation may explain those unexpected observations in the recent experiments. We also discover an "Anderson localization" of the nonlinear Hall effect. This work shows an emergent territory of the nonlinear Hall effect yet to be explored

Experimental Wireless Communication Using Chaotic Baseband Waveform

This work was supported by NSFC under Grants 61401354, 61172070, and 61502385, in part by the Key Basic Research Fund of Shaanxi Province under Grant 2016ZDJC0067, in part by the Natural Science Basic Research Plan in Shaanxi Province of China under Grant 2016JQ6015, in part by the Scientific and Technological Innovation Leading Talents Program of Shaanxi Province, and in part by the Foundation of Shaanxi Educational Committee under Grant 17JS086.Peer reviewedPostprin