How do I break a label up vertically in TIKZ?

When working with tikz, I’ve encountered this issue that I can’t get the axis labels to take up multiple lines. In some cases, the text on the axis is quite long, and so it becomes not very legible. In the example below, it would be better if the label

AAAAAAAAAAAA

was broken (i.e. extended vertically):

AAAAAA-

AAAAAA

How do you suggest I implement this change?

I have tried entering in AAAA//AAAA manually, but does not seem to be recognised by tikz.

begin{document}
centering
pgfplotstableread{
x   y    
AAAAAAAAAAAAAA   0.09
B   0.06 
C   0.04
D   0.02
}{mytablee}
begin{tikzpicture}
begin{axis} [
    ymin=0,
    symbolic x coords={AAAAAAAAAAAAAA,B,C,D},
    xtick=data
]
addplot
  plot [mark=none, black, dashed]
  table {mytablee};
end{axis} 
node[above,font=largebfseries] at (current bounding box.north) {Test};
node[below,font=large] at (current bounding box.south) {Sample};
end{tikzpicture}
end{document}

documentclass[border=3pt]{standalone}
usepackage{pgfplots}
pgfplotstableread{
x   y
AAAAAAAAAAAAAA   0.09
B   0.06
C   0.04
D   0.02
}{mytablee}

begin{document}

begin{tikzpicture}
begin{axis} [
    x tick label style={text width=1.7cm,align=center}, % <-- added
    ymin=0,
    symbolic x coords={AAAAAAAAAAAAAA,B,C,D},
    xtick=data
]
addplot
  plot [mark=none, black, dashed]
  table {mytablee};
end{axis}
node[above,font=largebfseries] at (current bounding box.north) {Test};
node[below,font=large] at (current bounding box.south) {Sample};
end{tikzpicture}
end{document}