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arXiv · 1803.01490

A cascading nonlinear magneto-optical effect in topological insulators

Richarj Mondal·Yuta Saito·Yuki Aihara·Paul Fons·Alexander V. Kolobov·Junji Tominaga·Shuichi Murakami·Muneaki Hase
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Abstract

Topological insulators (TIs) are characterized by possessing metallic (gapless) surface states and a finite band-gap state in the bulk. As the thickness of a TI layer decreases down to a few nanometer, hybridization between the top and bottom surfaces takes place due to quantum tunneling, consequently at a critical thickness a crossover from a 3D-TI to a 2D insulator occurs. Although such a crossover is generally accessible by scanning tunneling microscopy, or by angle-resolved photoemission spectroscopy, such measurements require clean surfaces. Here, we demonstrate that a cascading nonlinear magneto-optical effect induced via strong spin-orbit coupling can examine such crossovers. The helicity dependence of the time-resolved Kerr rotation exhibits a robust change in periodicity at a critical thickness, from which it is possible to predict the formation of a Dirac cone in a film several quintuple layers thick. This method enables prediction of a Dirac cone using a fundamental nonlinear optical effect that can be applied to a wide range of TIs and related 2D materials.

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Richarj Mondal, Yuta Saito, Yuki Aihara, Paul Fons, Alexander V. Kolobov, Junji Tominaga, Shuichi Murakami, Muneaki Hase. 2018-03-05. A cascading nonlinear magneto-optical effect in topological insulators. https://doi.org/10.1038/s41598-018-22196-x

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