MAGNETIC AND OPTICAL PROPERTIES OF TRANSPARENT RbNiF3

Magnetic and optical data on single‐crystal RbNiF3 are presented. We conclude that this material is ferrimagnetic, rather than antiferromagnetic as previously reported, with a transition temperature of 139°K and a saturation moment of 21 emu/g at 4.2°K. The basal plane is the preferred plane and the out‐of‐plane anisotropy is 106 ergs/cc. The Faraday rotation measured along the c axis at 77°K and 80% of magnetic saturation exhibits a peak value of 400° per cm at a wavelength of 4950 A and values of 250° to 50° per cm in the region 5000 to 6000 A where the optical absorption is lowest.