The magnetic hysteresis of 1-Dy was investigated by SQUID magnetometry with DC field sweep rates of 22 Oe s -1 in conjunction with an accurate calibration of the applied magnetic field (see Supporting Information; Figures and). At low temperatures we observe large steps at zero field, which are common for monometallic SMMs and arise from rapid magnetic reversal by QTM, consistent with the AC data . At 2 K we find 50% remanent magnetisation at zero field and a coercive field HC = 9.5 kOe (similar results are also observed for the dilute sample 5%Dy@1-Y, Figure );