Detection of axion dark matter heavier than an meV is hindered by its small wavelength, which limits the useful volume of traditional experiments. This problem can be avoided by directly detecting in-medium excitations, whose $\sim \mathrm{meV}–\mathrm{eV}$ energies are decoupled from the detector size. We show that for any target inside a magnetic field, the absorption rate of electromagnetically coupled axions into in-medium excitations is determined by the dielectric function. As a result, the plethora of candidate targets previously identified for sub-GeV dark matter searches can be repurposed as broadband axion detectors. We find that a kg yr exposure with noise levels comparable to recent measurements is sufficient to probe parameter space currently unexplored by laboratory tests. Noise reduction by only a few orders of magnitude can enable sensitivity to the QCD axion in the $\sim 10\mathrm{meV}–10\mathrm{eV}$ mass range.

中文翻译：

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磁化介质中轴子暗物质的吸收

比兆电子伏重的轴子暗物质的检测因其波长小而受到阻碍，这限制了传统实验的有用体积。这个问题可以通过直接检测介质内激励来避免，其$～\mathrm{兆伏}–\mathrm{电子伏特}$能量与探测器尺寸无关。我们表明，对于磁场内的任何目标，电磁耦合轴子对介质内激励的吸收率由介电函数决定。因此，之前为亚吉伏暗物质搜索而确定的大量候选目标可以重新用作宽带轴子探测器。我们发现，每年暴露一千克的噪声水平，与最近的测量结果相当，足以探测目前实验室测试尚未探索的参数空间。噪声仅降低几个数量级即可实现对 QCD 轴子的灵敏度$～10\mathrm{兆伏}–10\mathrm{电子伏特}$质量范围。