Magnetic structure of DyN: a ¹⁶¹Dy Mössbauer study

Conventional magnetometry yields a low temperature bulk magnetic moment of about 4μ_B/Dy³⁺ in an applied field of μ₀H =9 T for thin and thick dysprosium nitride (DyN) films. This is significantly lower than the maximum possible value of 10 μ_B/Dy³⁺. Ion-assisted deposition was used to grow 5.7-μm-thick rare earth nitride DyN films on organic Kapton® substrates. ¹⁶¹Dy Mössbauer spectroscopy (with its time scale on the order of nanoseconds) indicates thermal relaxation between fully stretched ±10μ_B levels of a low-lying Kramers doublet, which is inconsistent with the Dy³⁺ site's ideal cubic symmetry. However, a small tetragonal distortion [ϵ ≈ -0.024(10)] observed using x-ray powder diffraction is compatible with an additional rank 2 crystal field term, B⁰₂ ≈ -1.0(4)K, approaching the magnitude estimated to bring this about. The observed magnetic behavior can then be described using a two-level, molecular field model with θ_C set to ≈6-8K, which is substantially smaller than the accepted ordering temperature of T_C≈17-26K.