Magnetic polarons in low-density solid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$

We review the properties of polarons nucleated by vacancies in solid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and compare the magnetostatic contribution to the recently observed anomalies in the susceptibility for densities close to the melting curve. We show that the experimental results can be understood in terms of polaron effects if the experiments were sensitive only to the bulk paramagnetic solid and could not see the spins bound to the polarons. We also discuss the thermal relaxation of the spins in the polaron cloud and its importance for the analysis of the experiments. The magnetic contribution to the pressure P(H,T) due to the presence of polarons is calculated and new experiments are proposed to test for the predicted polaron properties.