AVS 61st International Symposium & Exhibition
    2D Materials Focus Topic Wednesday Sessions
       Session 2D+AS+EM+MI+MN+NS+TF-WeA

Paper 2D+AS+EM+MI+MN+NS+TF-WeA12
Mechanical Control of Structural Phase Transitions in Two-Dimensional Mo- and W- Dichalcogenide Monolayers

Wednesday, November 12, 2014, 6:00 pm, Room 310

Session: Properties of 2D Materials 
Presenter: Evan Reed, Stanford University
Authors: E.J. Reed, Stanford University
K.-A.N. Duerloo, Stanford University
Y. Li, Stanford University
Correspondent: Click to Email
Mo- and W- dichalcogenide compounds have a two-dimensional monolayer form that differs from graphene in an important respect: it can potentially have more than one crystal structure. Some of these monolayers exhibit tantalizing hints of a poorly understood structural metal-to-insulator transition with the possibility of long metastable lifetimes. If controllable, such a transition could bring an exciting new application space to monolayer materials beyond graphene. Here we discover that mechanical deformations provide a route to switching the thermodynamic stability between a semiconducting and a metallic crystal structure in these monolayer materials. We employ density functional and hybrid Hartree-Fock/density functional calculations including vibrational energy corrections to discover that single layer MoTe2 is an excellent candidate phase change material. We identify a range from 0.3% to 3% for the tensile strains required to transform MoTe2 under uniaxial conditions at room temperature. We elucidate the appropriate thermodynamic constraints for monolayers, which can differ from bulk materials. The potential for mechanical phase transitions is predicted for all six studied compounds. The potential application space ranges from catalysis to information storage and nanoscale electronics.