Antiferromagnetic phase transitions of the spinels, Zn1-xCuxCr2Se4;: 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 less than or equal to x less than or equal to 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 (T-N), 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 similar to 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.