Mössbauer Study of Ferrimagnetic Ordering in Nickel Ferrite and Chromium-Substituted Nickel Ferrite

Mössbauer-effect measurements in external magnetic fields show that the magnetic structure of ferrimagnetic Ni${\mathrm{Fe}}_2$${\mathrm{O}}_4$ is the collinear Néel type. Ni${\mathrm{Fe}}_{0.3}$${\mathrm{Cr}}_{1.7}$${\mathrm{O}}_4$ is shown to have a triangular structure with ${\theta }_A=20\mathrm{}\pm 10°$ and ${\theta }_B=50\mathrm{}\pm 4°$.