Antiferromagnetism in YbMn2Ge2-Mn magnetic sublattice

The magnetic structures of YbMn2Ge2 with the tetragonal ThCr2Si2 type struc ture have been investigated by neutron diffraction measurements over the te mperature range similar to 10-526 K, Rietveld refinements demonstrate that YbMn2Ge2 has a planar antiferromagnetic structure below T(NI)similar to 510 K with a canted antiferromagnetic structure below T(N2)similar to 185 K. T he canted antiferromagnetic ground state of YbMn2Ge2 has a Mn moment value of mu(Mn)(10 K)=3.03(5) mu(B), With the z-component of the moment mu(z)(10 K)=1.72(5) mu(B), corresponding to a canting angle relative to the c-axis o f theta(10 K)=55.4(9)degrees No evidence for magnetic ordering of the Yb la ttice is obtained although an unusual variation of the a-lattice parameter with temperature is observed. (C) 2000 Elsevier Science S.A, All rights res erved.