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Condensed Matter Seminars

ics Condensed Matter
Thursday, September 20, 2018
11:00 AM
Physics Building, Room 313
Nirmal Ghimire [Host: Bellave Shivaram]
George Mason University
""A materials-driven approach to the novel topological states of matter""
ABSTRACT:

Materials in condensed matter have recently been testbeds for several exotic particles, predicted but never realized, in high energy physics. The examples are skyrmions observed in magnetic textures. Weyl fermions in the low energy electronic excitations of Weyl semimetals and Majorana fermions in topological superconductors. These discoveries have not only allowed access to the fundamental physics of the rare particles but also driven large interest in the application of such exotic states to future technologies such as spin based electronics and quantum computation. Discoveries of topological states in materials have largely benefited from the precision of the electronic structure calculations in the weakly correlated systems. In the first part of this talk, I will discuss our resent results on two such predicted materials – 1) NbAs, one of the first generation Weyl semimetals [1-3] and 2) Pd3Pb, a novel topological material hosting multiple Dirac points and surface states [4]. While calculations are pretty accurate in weakly correlated systems, the topological states in presence of strong electron correlations are still not well understood. As such, materials can take a lead in this field. In the second part of the talk, I will briefly highlight our recent efforts in this area, driven by specific materials design criteria. As an illustration, I will discuss our study on the chiral-lattice antiferromagnet CoNb3S6 that has topological character in the electronic band structure, and manifests an unusually large anomalous Hall effect [5].

 

[1] N. J. Ghimire et al. J. Phys.: Condens. Matter 27, 152201 (2015).

[2] Y. Luo et al. Phys. Rev. B 92, 205134 (2015)

[3] P. J. W. Moll et al., Nat. Communs. 7, 12492 (2016).

[4] N. J. Ghimire et al., Phys. Rev. Materials 2, 081201(R) (2018)

[5] N. J. Ghimire et al., Nat. Communs. 9, 3280 (2018)

 

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