Ab-initio calculation of electronic stopping power along glancing swift heavy ion tracks in perovskites

TL;DR

This study uses ab-initio calculations combined with the Lindhard model to analyze how swift heavy ions create periodic nanodots on perovskite surfaces, revealing the role of electron density distribution and ion incidence angle.

Contribution

It introduces a novel model integrating ab-initio electron density data with Lindhard stopping to explain nanodot formation on insulator surfaces during ion irradiation.

Findings

Periodic electronic stopping power correlates with nanodot formation.

Surface pattern periodicity varies with ion incidence angle.

Electron density anisotropy influences energy deposition patterns.

Abstract

In recent experiments the irradiation of insulators of perovskite type with swift heavy ions under glancing incidence has been shown to provide a unique means to generate periodically arranged nanodots at the surface. The physical origin of these patterns has been suggested to stem from a highly anisotropic electron density distribution within the bulk. In order to show the relevance of the electron density distribution of the target we present a model calculation for the system Xe$^{+23}$ $\to$ SrTiO$_{3}$ that is known to produce the aforementioned surface modifications. On the basis of the Lindhard model of electronic stopping, we employ highly-resolved \emph{ab-initio} electron density data to describe the conversion of kinetic energy into excitation energy along the ion track. The primary particle dynamics are obtained via integration of the Newtonian equations of motion that are governed by a space- and time-dependent friction force originating from Lindhard stopping. The analysis of the local electronic stopping power along the ion track reveals a pronounced periodic structure. The periodicity length strongly varies with the particular choice of the polar angle of incidence and is directly correlated to the experimentally observed formation of periodic nanodots at insulator surfaces.