Sstrhsrtj

I have noticed that when I choose the tick marks of my graph to be outside, the first and the last ticks are thinner. Anybody know how to fix that? Here is the code I used. Below is the screenshot of the graph produced.

documentclass{article}



usepackage[T1]{fontenc}

usepackage[english]{babel}

usepackage[utf8]{inputenc}

usepackage[sc]{mathpazo}

usepackage{amsmath,amssymb,amsfonts,mathrsfs}

usepackage[amsmath,thmmarks]{ntheorem}

usepackage{graphicx}

usepackage{multirow}

usepackage{geometry}

usepackage{booktabs,makecell,longtable}

usepackage{lipsum}

usepackage{pdfpages}

usepackage{balance} 

usepackage{lastpage}

usepackage{amsmath,bm}

usepackage{textcomp}

usepackage{subeqnarray}

usepackage{float}

usepackage{mathtools}

usepackage{cite}

usepackage[export]{adjustbox}

usepackage{etoolbox}

usepackage{enumitem}

usepackage{lmodern}

usepackage[labelfont=bf,font=sf,labelsep=space]{caption}

usepackage{mathpazo}

usepackage[nottoc,notlot,notlof]{tocbibind}

usepackage{pgfplots}

usepackage{hyperref}

usepackage{tikz}

usetikzlibrary{tikzmark}



pgfkeys{/pgf/number format/.cd,1000 sep={}}





newcommand{myfont}{fontfamily{cmss}selectfont}% used with mathpazo 



DeclareMathOperator{Tr}{Tr}



setcounter{tocdepth}{2}



pgfplotsset{compat=1.5.1}

pgfplotsset{label style={font=Large},

            tick label style={font=Large}}



pgfplotsset{error bars/.cd,

    x dir=both, x explicit,

    y dir=both, y explicit,

    }

pgfplotsset{/pgfplots/error bars/error bar style={semithick,black}}

%pgfplotsset{/pgfplots/label shift={0pt}}





begin{document}





begin{figure}

centering



begin{tikzpicture}

begin{axis}[

    axis line style=semithick,

    width=9cm,

    height=7cm,

    only marks,

    %mark size=3pt,

    %legend image post style={mark options={scale=1.3,fill=white,line width=0.8pt}},

    legend style={at={(0.95,0.3)},draw=none},

    legend cell align={right},

    x tick style={black,semithick},

    x label/.style=

        {at={(ticklabel cs:0.5)},anchor=near ticklabel},

    xlabel={{$epsilon_n$} [{myfont -}]},

    xmin=0,xmax=1,

    xtick={0,0.5,...,1},

    xtick pos=bottom,

    %minor x tick num=1,

    xtick align=outside,

    %xminorgrids=true,

    every y tick/.style={black,semithick},

    y label style=

        {at={(ticklabel cs:0.5)},anchor=near ticklabel},

    ylabel={{$sigma_n$} [{myfont MPa}]},

    ymin=0,ymax=150,

    ytick={0,50,...,150},

    ytick pos=left,

    %minor y tick num=1,

    ytick align=outside,

    %yminorgrids=true,  

]

    addplot [sharp plot,red,very thick,mark=*,mark options={scale=2,blue,fill=white}]

    coordinates{

    (0.2,40)

    (0.4,70)

    (0.6,100)

    (0.8,130)

};



end{axis}

end{tikzpicture}

end{figure}





end{document}