Antiferromagnetic structure of ζ-MnN0.388 with 'ε-type' nitrogen ordering

The antiferromagnetic ordering in zeta-MnN0.388 - based on a h.c.p. arrangement of Mn with N on octahedral sites - was examined by neutron diffraction. The relative orientation of the ordered spins agrees with that described previously [Solid State Commun. 23 (1977) 147], though the direction of the magnetic moments relative to the crystallographic axes is found to be different, confirmed by the observation of a magnetic moment component along [001]. The arrangement of the ordered Mn moments is described by the magnetic space group C(P)2'/m' (a(m)=3(1/2)a(h.c.p.), b(m)=a(h.c.p.), c(m)=c(h.c.p.), beta(m)=90degrees). The magnitude of the moments is 1.68 mu(B) at 299 K and decreases continuously to 0 mu(B) at T-N = 353.7 K. The moments are tilted by 33degrees from the monoclinic a(m) axis towards the c(m) axis within the a(m)-c(m) plane. The direction of the ordered moments relative to the crystallographic axes remains virtually constant in the investigated temperature range. (C) 2003 Elsevier B.V. All rights reserved.