Soliton Generation in Negative Thermal Expansion Materials

Abstract

Strain solitons have been observed statically in several 2D materials and dynamically in substrate materials using ultrafast laser pulses. The latter case relies on lattice relaxation in response to ultrafast heating in a light-absorbing transducer material, a process which is sensitive to the thermal expansion coefficient. Here we consider an unusual case where the sign of the thermal expansion coefficient is negative, a scenario which is experimentally feasible in light of rapid and recent advances in the discovery of negative thermal expansion materials. We present numerical solutions to a nonlinear differential equation which has been repeatedly demonstrated to quantitatively model experimental data and discuss the salient results using realistic parameters for material linear and nonlinear elasticity. The solitons that emerge from the initial value problem with negative and positive thermal expansion are qualitatively different in several ways. The new case of negative thermal expansion gives rise to a nearly-periodic soliton train with chirped profile and free of an isolated shock front. We suggest this unanticipated result may be realized experimentally and assess the potential for certain applications of this generic effect.

Tailoring of thermal expansion and phase transition temperature of ZrW2O8 with phosphorus and enhancement of negative thermal expansion of ZrW1.5P0.5O7.75

“…There have many materials which exhibit low and negative thermal expansion (NTE). [1][2][3][4][5][6] They have been of considerable interest due to potential application in tailoring coefficient of thermal expansion. ZrW 2 O 8 is an amazing material because it exhibits a relatively large isotropic negative thermal expansion (NTE) over a wide temperature range of −272.7 • C to 777 • C. [7,8] However, there are some problems in ZrW 2 O 8 .…”

The azimuth manipulation of nonlocal photorefractive spatial solitons

“…The studies have shown that beams with high-order soliton structures are usually unstable in locally responsive media, and saturated nonlinear media cannot make beams with local structures, such as vortex beams, propagate stably, because the beams are prone to instability in the azimuth direction [23,24]. Although many materials exhibit non-local nonlinear properties, such as nematic liquid crystals [25], Bose-Einstein condensates [26], plasmas [27], thermally expanding materials [28], etc However, Snyder model is a simplified ideal model, and in real physical system, beam transmission will become more complex, and the theory and numerical simulation show that high-order solitons can not be stable transmission, so it is particularly important to explore the new model and study azimuth-modulated solitons.…”