Solid State and Structural Chemistry Unit
INDIAN INSTITUTE OF SCIENCE
BANGALORE – 560 012
Dr. Nitesh Kumar
Max Planck Institute for Chemical Physics of Solids
An overview of topological materials: From synthesis to applications
Date & Time : Monday 21st January 2019 at 11:00 AM
Venue : SSCU Auditorium
The rise of graphene in the last decade created a paradigm shift in the fundamental as well as application-oriented research of materials chemistry and condensed matter physics. Subsequently, a closely related field of topological materials prospered soon after the discovery of topological insulating states in bismuth chalcogenides. In the last few years, owing to the discovery of topological states in semimetals and metals (so called Dirac and Weyl semimetals), the area of topological materials has gained as a status of broad research area for chemists and physicists. However, the theoretical formulation of topological states is complex, they can be easily understood in terms of the behaviour of graphene. In this talk, I will introduce variety of topological states in simple compounds and try to understand their classifications based on symmetry, heaviness of the elements involved (spin orbit coupling) etc. Although these compounds are related to graphene fundamentally, they exhibit properties superior to graphene in many cases, for example extremely large mobility of electrons, high conductivity and record-breaking magnetic field induced increase in the electrical resistivity (positive magnetoresistance). Based on these excellent electronic properties, I will show that topological semimetals are also ideal candidates for hydrogen evolution catalysis.
Y. Xia et al., Observation of a large-gap topological-insulator class with a single Dirac cone on the surface. Nat. Phys. 5, 398 (2009).
L. M. Schoop et al., Chemical Principles of Topological Semimetals. Chem. Mater. 30 3155 (2018).
N. Kumar, C. Shekhar, S.-C. Wu et al., Observation of pseudo-two-dimensional electron transport in the rock salt-type topological semimetal LaBi. Phys. Rev. B (Rapid Communication) 93, 241106 (2016)
N. Kumar, Y. Sun, N. Xu et al., Extremely high magnetoresistance and conductivity in the type-II Weyl semimetals WP2 and MoP2. Nat. Commun. 8, 1642 (2017).
N. Kumar, K. Manna, Y. Qi et al., Unusual magnetotransport from Si-square nets in topological semimetal HfSiS. Phys. Rev. B (Rapid Communication) 95, 121109 (2017).
C. Shekhar, N. Kumar, V. Grinenko, S. Singh, R. Sarkar, H. Luetkens et al., Anomalous Hall effect in Weyl semimetal half Heusler compounds RPtBi (R = Gd and Nd). Proc. Natl. Acad. Sci. U S A 115, 9140 (2018).
E. Liu, Y. Sun, N. Kumar et al. Giant anomalous Hall effect in a ferromagnetic kagome-lattice semimetal. Nat. Phys. 14, 1125 (2018).
ALL ARE CORDIALLY INVITED TO ATTEND