[Tex/LaTex] Axis font size in pgf plots when using a large set of data

pgfplots

I am trying to plot a large set of data from a .dat file. The following is my code. I can plot the data using this code. But, I am not able to increase the size of the fonts used in the axis labels and title. I used I am using texworks and I use Lualatex to compile the code since the data is too large. Unfortunately, I am not able to attach the data file.

I am new to latex and pgfplots, any help would be appreciated.

\documentclass[landscape]{article}
\usepackage{tikz}
\usetikzlibrary{external}
\newenvironment{mytikz}{\begin{figure}[htp]
\centering
\begin{tikzpicture}}
{\end{tikzpicture}
\caption{}
\end{figure}}

\usepackage[active,tightpage]{preview}
\PreviewEnvironment{center}
\renewcommand{\PreviewBbAdjust}{0pt 0pt 0pt 0pt}
\usepackage[margin=0em]{geometry}
\usepackage[utf8]{inputenc}
\usepackage[english]{babel}
\usepackage{graphicx}
\usepackage{pgfplots}
\pgfplotsset{compat=1.8}

\begin{document}


\begin{mytikz}
\begin{center}
\begin{tikzpicture}
\begin{axis}[
    xlabel={Voltage ($V$)},
    ylabel={Current ($A$)},
    width=0.8\paperwidth, height=0.8\paperheight,]

   \addplot [
    color=black,
    solid,
    mark=diamond*,
    mark options={red}]
    table [col sep=comma]{Index_7_data_a.dat};
    \addplot [
    color=black,
    solid,
    mark=*,
    mark options={blue}]
    table [col sep=comma]{Index_7_data_b.dat};
    \addplot [
    color=black,
    solid,
    mark=pentagon*,
    mark options={green}]
    table [col sep=comma]{Index_7_data_c.dat};
%% Add a legend %%

\addlegendentry{$Phase A$};
\addlegendentry{$Phase B$};
\addlegendentry{$Phase C$};

\end{axis}

\end{tikzpicture}
\end{center}
\end{mytikz}

\end{document}

Best Answer

Have you tried xlabel={\Large Voltage $V$} etc. You can put pretty much any TeX command into PGF labels, even \parbox{}.