Magnetic Monopole Noise (Nature, 2019) (unpaywalled)

Magnetic monopoles are hypothetical elementary particles with quantized magnetic charge. [...] Here we report the development of a SQUID-based flux noise spectrometer and measurements of the frequency and temperature dependence of magnetic-flux noise generated by Dy2Ti2O7 crystals. We detect almost all of the features of magnetic-flux noise predicted for magnetic monopole plasmas7,8, including the existence of intense magnetization noise and its characteristic frequency and temperature dependence.