Commented review: UCu2Ge2 and UCu2Si2—compounds with only ferromagnetic ordering

Abstract

The slow acceptance by the scientific community of only ferromagnetic ordering belowTC inUCu2Ge2, and the general acceptance of the same magnetic situation inUCu2Si2, both withthe BCT ThCr2Si2-type crystallographic structure, are reviewed chronologically.Observations by neutron diffraction on annealed polycrystalline samples ofUCu2Ge2 have finally overcome many conclusions of antiferromagnetic (AF) ordering at lowtemperatures (LT), deduced from the magnetization overlooking the ferromagneticdomain structure. Observations by magnetization measurements on Cu-flux-grownUCu2Si2 single crystals, claiming ‘a 50 K AF transition below the 100 K ferromagnetic transition’,published recently in this journal (2003 J. Phys.: Condens. Matter 15 S1917), are shown tohave been misinterpreted by omitting any reference to ferromagnetic domainstructure. Comments are made on other features disputing the LT ferromagnetism ofUCu2Si2.