答案1
贝塞尔曲线是一种可能的解决方案(但不是唯一的解决方案,您也可以使用to[bend=right]
例如)。
\documentclass[tikz,border=3.14mm]{standalone}
\usetikzlibrary{arrows.meta}
\begin{document}
\begin{tikzpicture}
\draw[<->,>={Stealth[scale=1.5]}] (0,4) node[above left] {$n(k)$} |- (5,0) node[below right] {$k$};
\draw[dotted,cap=round,line width=0.5pt] (0,3) -| (3,0) node [below] {$k_F$};
\draw[line width=2pt,red]
(0,3) .. controls ++ (1,0) and ++ (-1,0.7) ..
(3,2.2) --
(3,1) .. controls ++ (0.5,-.5) and ++ (-0.5,0) ..
(4.8,0.2);
\draw[xshift=3mm,<->,>={Stealth[scale=1]},line width=0.5pt] (3,1) -- (3,2.2) node[midway,right] {\Large Z};
\end{tikzpicture}
\end{document}