  We propose an approach to search for axion dark matter with a specially
designed superconducting radio frequency cavity, targeting axions with masses
$m_a \lesssim 10^{-6} \text{ eV}$. Our approach exploits axion-induced
transitions between nearly degenerate resonant modes of frequency $\sim$ GHz. A
scan over axion mass is achieved by varying the frequency splitting between the
two modes. Compared to traditional approaches, this allows for parametrically
enhanced signal power for axions lighter than a GHz. The projected sensitivity
covers unexplored parameter space for QCD axion dark matter for $10^{-8} \text{
eV} \lesssim m_a \lesssim10^{-6} \text{ eV}$ and axion-like particle dark
matter as light as $m_a \sim 10^{-14} \text{ eV}$.
