Mu@C70: monitoring the dynamics of fullerenes from inside the cage

Prassides, Kosmas; Dennis, T. John S.; Christides, C.; Roduner, E.; Kroto, Harold W.; Taylor, Roger; Walton, D. R. M.

doi:10.1021/j100205a007

Cited by 51 publications

(17 citation statements)

References 8 publications

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“…However, charge transfer from the transition metal to the C 60 may cause a deformation of the cage as it is observed for the C 60 spin triplet state (38). This deformation may result in a slightly anisotropic hyperfine coupling of the endohedral muonium state, which then gives rise to the observed precession frequency in the megahertz range, similar as has been observed in C 70 (39).…”

Section: Systemsupporting

confidence: 49%

Emergent magnetism at transition-metal–nanocarbon interfaces

Ma’Mari

Rogers

Alghamdi

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Charge transfer at metallo-molecular interfaces may be used to design multifunctional hybrids with an emergent magnetization that may offer an eco-friendly and tunable alternative to conventional magnets and devices. Here, we investigate the origin of the magnetism arising at these interfaces by using different techniques to probe 3d and 5d metal films such as Sc, Mn, Cu, and Pt in contact with fullerenes and rf-sputtered carbon layers. These systems exhibit small anisotropy and coercivity together with a high Curie point. Low-energy muon spin spectroscopy in Cu and Sc-C 60 multilayers show a quick spin depolarization and oscillations attributed to nonuniform local magnetic fields close to the metallo-carbon interface. The hybridization state of the carbon layers plays a crucial role, and we observe an increased magnetization as sp 3 orbitals are annealed into sp 2 −π graphitic states in sputtered carbon/copper multilayers. X-ray magnetic circular dichroism (XMCD) measurements at the carbon K edge of C 60 layers in contact with Sc films show spin polarization in the lowest unoccupied molecular orbital (LUMO) and higher π*-molecular levels, whereas the dichroism in the σ*-resonances is small or nonexistent. These results support the idea of an interaction mediated via charge transfer from the metal and dz-π hybridization. Thin-film carbon-based magnets may allow for the manipulation of spin ordering at metallic surfaces using electrooptical signals, with potential applications in computing, sensors, and other multifunctional magnetic devices. emergent magnetism | molecular spintronics | interfacial magnetism | charge transfer | nanocarbon I nterfaces are critical in quantum physics, and therefore we must explore the potential for designer hybrid materials that profit from promising combinatory effects. In particular, the fine-tuning of spin polarization at metallo-organic interfaces opens a realm of possibilities, from the direct applications in molecular spintronics and thin-film magnetism to biomedical imaging or quantum computing. This interaction at the surface can control the spin polarization in magnetic field sensors, generate magnetization spin-filtering effects in nonmagnetic electrodes, or even give rise to a spontaneous spin ordering in nonmagnetic elements such as diamagnetic copper and paramagnetic manganese (1-11).The impact of carbon-based molecules on adjacent ferromagnets is not limited to spin filtering and electronic transport, but extends to induced changes in the metal anisotropy, magnetization, coercivity, and bias (12-14). Charge transfer and d(metal)-π(carbon) orbital coupling at the interface may change the density of states, spin population, and exchange of metallocarbon interfaces (4,15,16). The interaction between the molecule and the metal depends strongly on the morphology and specific molecular geometry (17, 18). It may lead to a change in the density of states at the Fermi energy DOS(E F ) and/or the exchange-correlation integral (I s ) as described by the Stoner criterion for ferr...

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Section: Systemsupporting

confidence: 49%

Emergent magnetism at transition-metal–nanocarbon interfaces

Ma’Mari

Rogers

Alghamdi

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“… 50 Other studies suggest that the plastic cubic phase with almost isotropic rotation of the cages axis persists even below room temperature. 51 – 53 In any case it has been recognized that below 270 K (top right), correlations develop between the orientations of neighbouring C 70 cages. The Figure shows the C 70 orientations organised in four 2×2 blocks.…”

Section: Discussionmentioning

confidence: 99%

Nuclear Magnetic Resonance of Hydrogen Molecules Trapped inside C₇₀ Fullerene Cages

et al. 2013

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We present a solid-state NMR study of H2 molecules confined inside the cavity of C70 fullerene cages over a wide range of temperatures (300 K to 4 K). The proton NMR spectra are consistent with a model in which the dipole–dipole coupling between the ortho-H2 protons is averaged over the rotational/translational states of the confined quantum rotor, with an additional chemical shift anisotropy δHCSA=10.1 ppm induced by the carbon cage. The magnitude of the chemical shift anisotropy is consistent with DFT estimates of the chemical shielding tensor field within the cage. The experimental NMR data indicate that the ground state of endohedral ortho-H2 in C70 is doubly degenerate and polarized transverse to the principal axis of the cage. The NMR spectra indicate significant magnetic alignment of the C70 long axes along the magnetic field, at temperatures below ∼10 K.

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“…The rotation dynamics in both the ordered and the disordered phases of C 70 were studied by a number of experimental techniques such as 13 C NMR [77][78][79], muon spin relaxation [80,81] and inelastic neutron scattering [82,83]. At very high temperatures, the orientational motion is described as quasi-isotropic, much like in C 60 .…”

Section: Solid State Structure Of Undoped Fullerenesmentioning

confidence: 99%

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

Buntar¹,

Sauerzopf²,

Weber³

1997

Aust. J. Phys.

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A review of some of the solid state and the magnetic properties of fullerenes is presented. We summarise and discuss experimental results on magnetism of pure C60, C70 and higher fullerenes. The main features of the structure and the magnetic properties of intercalated fullerenes, such as metallofullerenes, TDAE-C60 and polymeric A1C60, are presented. Attention is also paid to the mixed state properties of fullerene superconductors, especially to the evaluation of the critical fields and the characteristic lengths of these materials. Some new experimental results on this subject are also presented.

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Mu@C70: monitoring the dynamics of fullerenes from inside the cage

Cited by 51 publications

References 8 publications

Emergent magnetism at transition-metal–nanocarbon interfaces

Emergent magnetism at transition-metal–nanocarbon interfaces

Nuclear Magnetic Resonance of Hydrogen Molecules Trapped inside C₇₀ Fullerene Cages

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

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Mu@C70: monitoring the dynamics of fullerenes from inside the cage

Cited by 51 publications

References 8 publications

Emergent magnetism at transition-metal–nanocarbon interfaces

Emergent magnetism at transition-metal–nanocarbon interfaces

Nuclear Magnetic Resonance of Hydrogen Molecules Trapped inside C70 Fullerene Cages

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

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Product

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Nuclear Magnetic Resonance of Hydrogen Molecules Trapped inside C₇₀ Fullerene Cages