Phase Diagram for Spontaneous Nuclear Magnetic Ordering in Copper

Abstract
The static susceptibility of a single-crystal copper specimen has been measured at nanokelvin temperatures, parallel and perpendicular to the external magnetic field B. Below Bc=0.27 mT, three different antiferromagnetically ordered regions are described at small values of entropy S. The BS phase diagram is presented. Metastabilities and the observed nonadiabaticity during the final stages of demagnetization are discussed.