How to prevent superscript getting too close to line above

The below code is working but the superscript H appears to be too close to the line above.

How can I put some space in between the H and the line right above it? Thx.

\documentclass{article}

\usepackage{array}

\begin{document}

$\left( \begin{array}{c|c} { I } & { 0 } \\ \hline { 0 } & { I - \frac{1}{\tau_1} \left( \begin{array}{c} { 1 } \\ \hline { u_{2} } \end{array} \right) \left( \begin{array}{c} { 1 } \\ \hline { u_{2} } \end{array} \right)^H } \end{array} \right)$

\end{document}

• Why don't you use \dfrac instead of nesting arrays in array? – Bernard Apr 30 at 11:49
• @Bernard that would be better markup probably but the superscript H would still be close the the hline in the outer array (I think) – David Carlisle Apr 30 at 11:52
• @DavidCarlisle: I know this wouldn't solve the problem, but I wondered whether there was a specific reason. – Bernard Apr 30 at 12:06
• @Bernard Thx for the suggestion. I had not used \dfrac before but upon trial my impression is that the use of an array and \hline would convey what is meant by this formula better given the longer separating line and also help me maintain better code consistency across vectors or matrices with different number of elements. – Alper Apr 30 at 12:30
• I've posted a solution with a short code with a longer line in fraction (easily turned into a macro) and a=vertical spacing for the exponent. – Bernard Apr 30 at 12:48

One simple way is to add a blank line and back up a bit (although this does over-print the vertical rule)

\documentclass{article}

\usepackage{array}

\begin{document}

\$
\begin{array}{c|c}
{ I } & { 0 } \\ \hline
\end{document}