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Nano Lett. 2018 Dec 12;18(12):7794-7800. doi: 10.1021/acs.nanolett.8b03559. Epub 2018 Nov 12.

Opto-Mechanics Driven Fast Martensitic Transition in Two-Dimensional Materials.

Author information

1
Department of Nuclear Science and Engineering , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States.
2
Center for Advancing Materials Performance from the Nanoscale, State Key Laboratory for Mechanical Behavior of Materials , Xi'an Jiaotong University , Xi'an 710049 , China.
3
Department of Materials Science and Engineering , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States.

Abstract

Diffusional phase-change materials, such as Ge-Sb-Te alloys, are used in rewritable nonvolatile memory devices. But the continuous pursuit of readout/write speed and reduced energy consumption in miniaturized devices calls for an optically driven, diffusionless phase change scheme in ultrathin materials. Inspired by optical tweezers, in this work, we illustrate theoretically and computationally that a linearly polarized laser pulse with selected frequency can drive an ultrafast diffusionless martensitic phase transition of two-dimensional ferroelastic materials such as SnO and SnSe monolayers, where the unit-cell strain is tweezed as a generalized coordinate that affects the anisotropic dielectric function and electromagnetic energy density. At laser power of 2.0 × 1010 and 7.7 × 109 W/cm2, the transition potential energy barrier vanishes between two 90°-orientation variants of ferroelastic SnO and SnSe monolayer, respectively, so displacive domain switching can occur within picoseconds. The estimated adiabatic thermal limit of energy input in such optomechanical martensitic transition (OMT) is at least 2 orders of magnitude lower than that in Ge-Sb-Te alloy.

KEYWORDS:

Opto-mechanics; density functional theory; dielectric function; ferroelasticity/ferroelectricity; martensitic phase transition; two-dimensional materials

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