Abstract
Topological insulators insulate in the bulk but exhibit robust conducting edge states protected by the topology of the bulk material. Here, we design a colloidal topological insulator and demonstrate experimentally the occurrence of edge states in a classical particle system. Magnetic colloidal particles travel along the edge of two distinct magnetic lattices. We drive the colloids with a uniform external magnetic field that performs a topologically non-trivial modulation loop. The loop induces closed orbits in the bulk of the magnetic lattices. At the edge, where both lattices merge, the colloids perform skipping orbits trajectories and hence edge-transport. We also observe paramagnetic and diamagnetic colloids moving in opposite directions along the edge between two inverted patterns; the analogue of a quantum spin Hall effect in topological insulators. We present a robust and versatile way of transporting colloidal particles, enabling new pathways towards lab on a chip applications.
Highlights
Topological insulators insulate in the bulk but exhibit robust conducting edge states protected by the topology of the bulk material
Paramagnetic colloidal particles of diameter 2.8 μm are immersed in water and move at a fixed elevation above the pattern
Since the edge between both patterns is located in opposite directions from the center of the corresponding orbits, the skipping directions are antiparallel. This results in skipping orbits along the edge where both types of particles move on opposite sides of the edge in opposite directions. This represents the colloidal analogue of the quantum spin Hall effect[21], in which electrons of opposite spins move in different directions along the same edge
Summary
Johannes Loehr[1], Daniel de las Heras 1, Adam Jarosz[2], Maciej Urbaniak[2], Feliks Stobiecki[2], Andreea Tomita[3], Rico Huhnstock[3], Iris Koch[3], Arno Ehresmann[3], Dennis Holzinger3 & Thomas M. We design a colloidal topological insulator and demonstrate experimentally the occurrence of edge states in a classical particle system. At the edge, where both lattices merge, the colloids perform skipping orbits trajectories and edge-transport. In the semi-classical picture of the quantum Hall effect, the magnetic field enforces the electrons to perform closed cyclotron orbits in the bulk of the material. We present here the experimental observation in a colloidal system of skipping orbits and edge states. These edge states allow for a robust transport of colloids along the edges and the corners of the underlying magnetic lattice
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
