latex large division sign in a math formula - Stack Overflow

$\left. {\frac{a_1}{a_2}} \middle/ {\frac{b_1}{b_2}} \right. $

\documentclass[conference]{IEEEtran}

\title{A title}

\makeatletter
\newcommand{\linebreakand}{%
  \end{@IEEEauthorhalign}
  \hfill\mbox{}\par
  \mbox{}\hfill\begin{@IEEEauthorhalign}
}
\makeatother

\author{
  \IEEEauthorblockN{1\textsuperscript{st} Given Name Surname}
  \IEEEauthorblockA{\textit{dept. name of organization (of Aff.)} \\
    \textit{name of organization (of Aff.)}\\
    City, Country \\
    email address}
  \and
  \IEEEauthorblockN{2\textsuperscript{nd} Given Name Surname}
  \IEEEauthorblockA{\textit{dept. name of organization (of Aff.)} \\
    \textit{name of organization (of Aff.)}\\
    City, Country \\
    email address}
  \and
  \IEEEauthorblockN{3\textsuperscript{rd} Given Name Surname}
  \IEEEauthorblockA{\textit{dept. name of organization (of Aff.)} \\
    \textit{name of organization (of Aff.)}\\
    City, Country \\
    email address}
  \linebreakand % <------------- \and with a line-break
  \IEEEauthorblockN{4\textsuperscript{th} Given Name Surname}
  \IEEEauthorblockA{\textit{dept. name of organization (of Aff.)} \\
    \textit{name of organization (of Aff.)}\\
    City, Country \\
    email address}
  \and
  \IEEEauthorblockN{5\textsuperscript{th} Given Name Surname}
  \IEEEauthorblockA{\textit{dept. name of organization (of Aff.)} \\
    \textit{name of organization (of Aff.)}\\
    City, Country \\
    email address}
}

\begin{document}

\maketitle

\end{document}

\author{
  \IEEEauthorblockN{Hrittik Raj Barua}
  \IEEEauthorblockA{\textit{Department of Electrical and Electronic Engineering} \\
    \textit{University of Science and Technology Chittagong}\\
    Chittagong, Bangladesh \\
    hrittik.rb2000@yahoo.com}
  \and
  \IEEEauthorblockN{Mohammad Mainul Hasan}
  \IEEEauthorblockA{\textit{Department of Electrical and Electronic Engineering} \\
    \textit{University of Science and Technology Chittagong}\\
    Chittagong, Bangladesh \\
    mainulhasan@ustc.ac.bd}
  \and
  \IEEEauthorblockN{Imtiaz Akber Chowdhury}
  \IEEEauthorblockA{\textit{Department of Electrical and Electronic Engineering} \\
    \textit{University of Science and Technology Chittagong}\\
    Chittagong, Bangladesh \\
    eee.imtiazakber@ustc.ac.bd}
  %\linebreakand % <------------- \and with a line-break
  \and
  \IEEEauthorblockN{Arpan Dey}
  \IEEEauthorblockA{\textit{Department of Electrical and Electronic Engineering} \\
    \textit{University of Science and Technology Chittagong}\\
    Chittagong, Bangladesh \\
    arpande.official@yahoo.com}
  \and
  \IEEEauthorblockN{Tridib Banik}
  \IEEEauthorblockA{\textit{Department of Computer Science \& Engineering} \\
    \textit{Assam Downtown University}\\
    Assam, India \\
    Tridibbanik34@gmail.com}
  \and
  \IEEEauthorblockN{Mohammad Rakibul Hoque Khan}
  \IEEEauthorblockA{\textit{Department of Electronics \& Telecommunications Engineering} \\
    \textit{International Islamic University Chittagong}\\
    Chittagong, Bangladesh \\
    rakibulhoquekhan@gmail.com}
}