The rare earth alloy ${\mathrm{Ho}}_{0.4}$${\mathrm{Gd}}_{0.6}$ was examined under uniaxial pressure applied along the c axis by means of magnetic susceptibility vs temperature. At ambient pressure the compound happened to be ferromagnetic at all temperatures where magnetic ordering occurs. Nevertheless, at pressures larger than ${\mathrm{p}}^{\mathrm{*}}$=700 bars there is clear evidence of an antiferromagnetic phase (likely to be helical one) that occurs just below the magnetic ordering temperature. This result is consistent with the hypothesis that the c/a ratio is the crucial parameter for the occurrence of helical structure in heavy rare-earth metals.

DOI:https://doi.org/10.1103/PhysRevB.55.14107