Antiferromagnetic phase transitions of the spinels, Zn 1-x Cu x Cr 2 Se 4 ; x =0.50 and 0.60

Magnetic and crystallographic properties have been studied by neutron powder diffraction and measurements of magnetic properties for the spinels Zn1-xCuxCr2Se4; 0.50≤x≤1.0. It is found that the spinels with x=0.50 and 0.60 show an antiferromagnetic phase transition at about 24 K and 28 K (TN), respectively, in addition to a ferromagnetic phase transition at about 420 K. Zn1-xCuxCr2Se4 with x=0.50 and 0.60 shows satellite-like magnetic reflections having indices of (h±Q, k, l); Q∼0.470 and 0.493 at 2 K, respectively. It is considered that the intermediate ferromagnetic phase does not result from a conical spin order of Cr3+ ions.