Make the plus sign in citations a superscript

preambles/packages.tex

@@ -27,6 +27,7 @@
 
 % biblatex 
 \usepackage[style=ieee-alphabetic, hyperref,backend=bibtex, mincitenames=1, maxcitenames=4,language=english,giveninits=true]{biblatex}
+\renewcommand*{\labelalphaothers}{${}^+$}
 % \usepackage[citestyle=authoryear,bibstyle=numeric,hyperref,backend=biber, minnames=3, maxnames=3,indexing=true,language=english,giveninits=true]{biblatex}
 % \setbeamercolor{bibliography item}{fg=KITgreen}
 \setbeamercolor{bibliography entry title}{fg=kit-green}