Spontaneous nuclear magnetic ordering in copper and silver at nano- and picokelvin temperatures

Pertti Hakonen*, Olli V. Lounasmaa, Aarne Oja

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

39 Citations (Scopus)


Owing to the weak mutual interactions, spontaneous nuclear magnetic ordering in metallic copper and silver occurs at 60 nK and 560 pK, respectively. These extremely low spin temperatures can be reached by two-stage adiabatic nuclear demagnetization. Spin ordering has been investigated by employing magnetic susceptibility measurements on copper and silver and by using neutron diffraction techniques on copper. Three antiferromagnetic phases in the field-entropy plane have been discovered in copper, caused by competition between the dipolar and Ruderman-Kittel exchange interactions; only one ordered state has been found in silver. Negative spin temperatures have been produced in silver as well, and a clear ferromagnetic tendency was observed when T <0. The theoretically calculated spin-spin interactions, ordering temperatures, magnetic phase diagrams and ordered spin structures are in good overall agreement with experimental data for these two metals.

Original languageEnglish
Pages (from-to)394-412
Number of pages19
JournalJournal of Magnetism and Magnetic Materials
Issue number1-3
Publication statusPublished - 1991
MoE publication typeA1 Journal article-refereed


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