Recent experimental results on antiferromagnetic and ferromagnetic ordering in silver at nanokelvin temperatures are reviewed. The dominant interaction between nuclear spins is the Ruderman-Kittel exchange which leads to spontaneous antiferromagnetic ordering below the record-low Néel temperatureTn= 560 pK. AboveTc=—1.9 nK, ferromagnetic order has beenfound, which is a consequence of the fact that the spin system tries tomaximize its Helmholtz free energy. The ferromagnetic ordering isobserved as a saturation of the susceptibility to — 1, which is caused by theformation of plate-shaped domains. Except for the re-entrant form of theantiferromagnetic phase diagram atT >0, the overall agreement betweenexperimental and theoretical results is good.
- magnetic ordering
- positive and negative spin