Non-Arrhenius Behavior of Surface Diffusion Near a Phase Transition Boundary

TL;DR

This paper investigates how surface diffusion deviates from Arrhenius behavior near a phase transition, linking it to microscopic jump dynamics and suggesting STM can probe these effects.

Contribution

It reveals that non-Arrhenius diffusion near phase transitions is governed by microscopic jump distributions, providing a microscopic basis for macroscopic diffusion anomalies.

Findings

Diffusion behavior deviates from Arrhenius law near phase transition.

Microscopic jump waiting-time distribution W(t) determines diffusion dynamics.

STM measurements can access the microscopic information related to diffusion.

Abstract

We study the non-Arrhenius behavior of surface diffusion near the second-order phase transition boundary of an adsorbate layer. In contrast to expectations based on macroscopic thermodynamic effects, we show that this behavior can be related to the average microscopic jump rate which in turn is determined by the waiting-time distribution W(t) of single-particle jumps at short times. At long times, W(t) yields a barrier that corresponds to the rate-limiting step in diffusion. The microscopic information in W(t) should be accessible by STM measurements.