Antiferromagnetic Correlations and Weak Ferromagnetism in aTDAE+−C60−Single Crystal

Abstract

The ESR spectra of a TDAE 1 -C 2 60 single crystal show the existence of antiferromagnetic (AFM) correlations between the unpaired spins on neighboring C 2 60 ions along the c axis and spin canting which leads, below T c , to weak ferromagnetism along a direction perpendicular to the c axis. This suggests that a Dzyaloshinsky-Moriya type mechanism is responsible for ferromagnetic ordering rather than itinerant ferromagnetism. The incomplete orientational ordering of the C 2 60 ions leads to a distribution of exchange coupling constants resulting in spin-glass type behavior which coexists with long range ferromagnetic ordering below T c . The observation of AFM correlations may help to understand why the same basic molecule C 60 can support such different phenomena as ferromagnetism (in TDAE-C 60 ) and superconductivity (in, e.g., K 3 C 60 ).

Molecular Magnetism with Fullerene Building Blocks: the race is on for High T

“…The predicted net magnetization in this model would point perpendicular to the direction of the strongest (AFM) exchange interaction direction which is in apparent agreement with susceptibility anisotropy measurements on single crystals [21]. This suggestion is very appealing theoretically, but nevertheless some pieces of the puzzle are still missing.…”

Solid State and Magnetic Properties of Pure, Intercalated and Superconducting Fullerenes

“…Spin glass features were seen in AC susceptibility [101], capacity [102], electron spin resonance (ESR) [103] and muon rotation (µSR) [104] measurements. More recently, long range order was inferred from the rather narrow local magnetic field distribution probed by implanted muons [105,106], and from single crystal ESR [107]. The strongly anisotropic ESR line intensity was interpreted in terms of an antiferromagnetic exchange along the c axis, leading to weak ferromagnetism of the Dzyaloshinsky-Moria type [108,109].…”

Dzyaloshinskii-Moriya interaction and spin reorientation transition in the frustrated kagome lattice antiferromagnet

“…[36][37][38] It has been experimentally observed in spin frustrated perovskite cuprates, [39][40][41][42][43][44][45][46] the pyrochlore antiferromagnet Cu 4 O 3 , 47 and molecule-based magnets. [48][49][50][51][52] The microscopic calculations of the DM interaction on the kagome lattice have been carried out by Elhajal et al 36 by applying Moriya's formulation. 38 To first approximation, the spin Hamiltonian is given by:…”