Strain in 2D materials

Date: 22 May 2018

Venue: Campus Groenenborger, Building U, Room 244 - Groenenborgerlaan 171 - 2020 Antwerpen (route: UAntwerpen, Campus Groenenborger)

Time: 4:00 PM

Organization / co-organization: Condensed Matter Theory

Short description: Condensed Matter Theory lecture presented by Dr Slavisa Milovanovic



Strain in 2D materials

Abstract
In this talk, I will review the most important effects of strain in different 2D materials. The basic terminology is given in the introduction. Here I will explain what is strain/stress tensor, the difference between strain and stress, displacement field, Young’s modulus, Poisson’s ratio, etc… Furthermore, I will give a short overview about the importance of strain in the semiconductor industry.

The main part of the talk is dedicated to strain in 2D materials. Due to their strong bonds, most of the 2D materials can be considerably stretched.  This stretch is accompanied with a significant change of their electronic and vibrational properties.  I will show on the example of graphene that straining a 2D material is very similar to applying a gauge field. As a consequence, a pseudo-magnetic field arises in the structure. The strength and the profile of the field are determined by the strain profile. Hence, “strain engineering” developed as a promising path to alter properties of 2D materials in the desired manner.

Apart from the graphene, other 2D materials show interesting features when strained. Here, I would mention semiconducting TMDs where the size of the band gap can be modified by strain.  Furthermore, these materials proved to be good candidates as quantum emitters. Density functional theory showed that monolayer BN and many of the TMDs are piezoelectric, unlike their bulk counterparts. Recently, it was shown that stacking different monolayer materials with similar lattice constants on top of each other results with an out-of-plane rippling of the structure caused by the interaction between two layers. All these effects will be discussed in the lecture.



Contact email: lucian.covaci@uantwerpen.be

Link: http://cmt.uantwerpen.be