\begin{tikzpicture} 
\begin{axis}[
axis equal,
axis lines*=middle,
enlargelimits = false,
xmax=1.5,
xmin=-1.5,
ymin=-1.5,
ymax=1.5,
axis line style={->,>=stealth},
xlabel={$\mathrm{Re}\{z\}$},
ylabel={$\mathrm{Im}\{z\}$},
every axis x label/.style={
    at={(ticklabel* cs:1)},
    anchor=north,
},
every axis y label/.style={
    at={(ticklabel* cs:1)},
    anchor=south,
},
xtick={0.5},
ytick={-0.5, 0.5},
xticklabel style = {xshift=-0.2cm},
every outer y axis line/.append style={white!15!black},
every y tick label/.append style={font=\color{white!15!black}},
legend style={draw=white!15!black,fill=white,legend cell align=left}]
\addplot[line width=1pt,mark=*, only marks, mark size = 3pt, mark options={fill=black!20}] coordinates {(0.5, 0.5) (0.5, -0.5)};
\addplot[line width=1pt,mark=x, only marks, mark size = 3pt] coordinates {(0, 0)};
\node at (axis cs: 0.1, 0.1) {$2$};
\draw (axis cs:0,0) circle [black, line width=2pt, radius=1];
\end{axis}
\end{tikzpicture}
