The magnetic structure of EuGe2

The magnetic ordering of the trigonal compound EuGe2 has been studied using 151Eu Mössbauer spectroscopy and neutron powder diffraction. The europium in EuGe2 is divalent and orders antiferromagnetically (AF) below TN∼49 K giving a hyperfine field of 24.4(1) T at 4.6 K. The thermal evolution of the spectra shows no evidence for changes to the structure or slow paramagnetic dynamics as TN is approached from below. Analysis of the neutron diffraction data shows that EuGe2 orders as an A-type AF with the 7.1(2)μB Eu2+ moments ordered as ferromagnetic sheets within the ab-plane and AF coupled along the c-axis, forming a magnetic cell that is doubled along the crystallographic c-axis.