Microscopic Studies of Novel 2D Materials

Abstract

Magnetic skyrmions are particle-like spin textures that can be found in chiral magnets with non-trivial topology. At zero temperature, skyrmions often form triangular lattices similar to other two-dimensional solids. Using Monte-Carlo simulations, we study both the temperature induced and applied magnetic field induced transition from solid to liquid for two-dimensional magnetic skyrmions. We compare the nature of this transition to that of typical two-dimensional solids which may also experience two-step melting passing through a hexatic phase before transitioning to a liquid [1]. We show by examining the rate of decay of the system correlation functions, we can clearly identify solid and liquid phases, as well as a potential intermediate phase. Comparing the rates of decay of the correlation functions with skyrmion configurations sampled in the intermediate phase suggests that when varying the magnetic field there is some evidence of a potential hexatic phase, but this is not conclusive. The occurrence of hysteresis when comparing melting and freezing scenarios of the temperature mediated transition indicates a possible first-order transition; whereas, the is very little evidence of hysteresis when varying the magnetic field, which suggests that the nature of the transition may change depending on which parameter is being varied.

Date of Award	31 Dec 2021
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Niels Walet (Supervisor) & Judith McGovern (Supervisor)