Implantation studies of low-energy positive muons in niobium thin films

TL;DR

This study uses low-energy muon spin spectroscopy to measure the implantation profiles of positive muons in niobium thin films, validating simulation models with updated stopping data for improved accuracy.

Contribution

It provides experimental validation of muon implantation profiles in niobium films using updated Monte Carlo simulations, enhancing the reliability of muon stopping predictions.

Findings

Simulations with updated stopping data agree well with experimental measurements.

The study improves understanding of muon behavior in thin film materials.

Implications for future muon-based material studies are discussed.

Abstract

Here we study the range of keV positive muons $\mu^+$ implanted in Nb$_2$O$_5$($x$ nm)/Nb($y$ nm)/SiO$_2$(300 nm)/Si [$x$ = 3.6 nm, 3.3 nm; $y$ = 42.0 nm, 60.1 nm] thin films using low-energy muon spin spectroscopy (LE-$\mu$SR). At implantation energies 1.3 keV $\leq E \leq$ 23.3 keV, we compare the measured diamagnetic $\mu^+$ signal fraction $f_{\mathrm{dia.}}$ against predictions derived from implantation profile simulations using the TRIM.SP Monte Carlo code. Treating the implanted $\mu^+$ as light protons, we find that simulations making use of updated stopping cross section data are in good agreement with the LE-$\mu$SR measurements, in contrast to parameterizations found in earlier tabulations. Implications for other studies relying on accurate $\mu^+$ stopping information are discussed.