### Topological crystals as a new paradigm

Tanda, S *(Hokkaido University)*

Monday 23 July 2012, 16:45-17:05

Seminar Room 1, Newton Institute

#### Abstract

We report the discovery of Mobius, Ring, Figure-8, and Hopf-link Crystals in NbSe3, conventionally grown as ribbons and whiskers. We also reveal their formation mechanisms of which two crucial components are the spherical selenium (Se) droplet, around which a NbSe3 bar wraps due to surface tension, and the monoclinic (P2(1)/m) crystal symmetry inherent in NbSe3, which induces a twist in the strip when bent. Our crystals provide a non-fictitious topological Mobius world governed by a non-trivial real-space topology. We class ed these topological crystals as an intermediary between condensed matter physics and mathematics.
References [1]A Mobius strip of single crystals, S. Tanda et al., Nature 417, 397 (2002). [2]Formation and growth of NbSe3 topological crystals, T. Tsuneta and S.Tanda J. Cryst. Growth 267, 223 (2004). [3]Topologically linked crystals, T. Matsuura et al., J. Cryst. Growth 297, 157 (2006). [4]Topological eff ects of the superconducting vortex state in a TaSe3 ring crystal, G. Kumagai et al., Phys. Rev. B81, 184506 (2010). [5]Chiral Charge-Density waves, J. Ishioka et al., Phys. Rev. Lett 105, 176401 (2010). [6]Topology-change surgery for crystals, T. Matsuura et al., Phys. Rev. B83 174113 (2011).