High-frequency magnetic resonance measurements (νL =9.6-420 GHz) were employed to investigate the low-temperature antiferromagnetic ground state of the (C H3 N H2) K3 C60 fulleride. The frequency and temperature dependence of the intensity, linewidth, and center of the resonance signal detected below TN are characteristic of antiferromagnetic resonance (AFMR). The AFMR intensity is consistent with an ordered magnetic moment of μeff =0.7 (1) μB C60, while the narrowing of the AFMR signal with increasing resonance frequency can be modeled with a spin-flop field of Hsf =840 (80) G and a g -factor anisotropy of δγ=710 (50) ppm. We stress that the spin-flop field is reduced compared to the ammoniated analog (N H3) K3 C60 on the account of reduced C60 3- - C60 3- exchange interactions. Differences in the level of the anisotropic expansion between C H3 N H2 and N H3 cointercalated fullerides are likely to be responsible for the differences in the electronic structure between the two systems and ultimately may account for the reduced Néel temperature in (C H3 N H2) K3 C60.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2008 Jan 3|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics