Scanning tunneling spectroscopy of small Ce-doped endohedral fullerenes on HOPG

Klingeler, R.; Breuer, C; Wirth, Ingo; Blanchard, A.J.; Bechthold, P. S.; Neeb, M.; Eberhardt, W.

doi:10.1016/j.susc.2004.01.039

Cited by 9 publications

(9 citation statements)

References 30 publications

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“…18,19 Furthermore, an opening of an energy gap at 28 K is suggested by scanning tunneling microscopy of a single C 60 -encapsulated La cluster (i.e., La@C 60 ), 19 which is suggested to be metallic. Subsequently, lanthanide-metal-doped C 60 materials were studied and superconducting properties were reported for Sm x C 60 (T c = 8 K).…”

Section: Introductionmentioning

confidence: 99%

Electronic phase transition of the valence-fluctuating fulleride Eu2.75C60

et al. 2011

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The electronic properties of Eu 2.75 C 60 are studied using magnetic susceptibility and electron spin resonance (ESR) from 2 to 300 K. Both the magnetic susceptibility and the ESR parameters clearly show an anomaly around the valence transition temperature, T V = 70 K. The magnetic susceptibility shows weak temperature dependence above T V , while it changes drastically to Curie-Weiss behavior below T V . The low-temperature susceptibility can be reproduced by assuming the moment of free Eu 2+ ions. This result reveals that Eu 2.75 C 60 changes from the intermediate valence state to the divalent state below T V . Although ESR signals above T V should be attributed to conduction electrons, the ESR intensity below T V follows the Curie-Weiss law with a distinct increase in the g-factor. This should be associated with a strong localization of π electrons. We also found that, below ∼17 K, the isothermal magnetization exhibits a weak hysteresis and thermoremanent magnetization appears. These results suggest that valence-ordered Eu 2.75 C 60 undergoes antiferromagnetic ordering with a weak ferromagnetic component at the Néel temperature, T N = 17 K.

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Section: Introductionmentioning

confidence: 99%

Electronic phase transition of the valence-fluctuating fulleride Eu2.75C60

et al. 2011

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“…It was concluded that hybridizations were found between the Mn, Fe, Co, and Ni 3d valence orbitals and the C 60 orbital, and the metal atom inside fullerene cage represented the preferential position. In addition, some experimental investigations on the endohedral metallofullerenes have been observed by experimental techniques 23–28. For example, Shinohara 23 prepared the endohedral metallofullerenes, produced from the Group 2 and Group 3 metal atoms such as Sc, Y, La, Ca, Sr, and Ba as well as lanthanide metallofullerenes (Ce−Lu), with the X‐ray diffraction, 13 C NMR and ultra‐high vacuum scanning tunneling microscopy (UHV‐STM) techniques.…”

Section: Introductionmentioning

confidence: 99%

Theoretical study on the smallest endohedral metallofullerenes: TM@C₂₀ (TM = Ce and Gd)

Sun

et al. 2010

Int J of Quantum Chemistry

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ABSTRACT:The structure, electronic property, and infrared spectroscopy of endohedral metallofullerenes TM@C 20 (TM ¼ Ce and Gd) have been systematically investigated with the aid of the hybrid DFT-B3LYP functional. It is found that in the endohedral metallofullerenes the average CAC bond lengths are obvious longer than those of empty cage. The frontier orbital analyses show that the endohedral metallofullerene Gd@C 20 has the high-thermodynamic stability. Natural population analysis also tells us that only in the Ce@C 20 , the Ce atom acts as an electron acceptor with the negative charges, and the 4f orbitals of Ce and Gd atoms have a significant contribution in the formation of chemical bonding. Additionally, the analyses of harmonic vibrational frequencies reveal that when the TM atoms are encapsulated into the C 20 cage, the strongest absorption peaks are characterized by a mixture of TMÀC bending and CAC stretching vibrations.

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“…Chemists are highly interested in why and how these otherwise extremely unstable fullerene species were stabilized. Finally, some unconventional fullerene materials, e.g., the solid of C 36 3 and Ce@C 44 , etc . were revealed to own novel electronic properties and superconductivity, so they may be found in direct applications in future.…”

Section: Introductionmentioning

confidence: 99%

C₆₄H₄: Production, Isolation, and Structural Characterizations of a Stable Unconventional Fulleride

et al. 2006

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Unconventional fullerenes are those smaller than C(60) or those intermediate between C(60) and C(70), which are not stable in structure as none of the unconventional fullerene isomers satisfying the "isolated-pentagon-rule" (IPR). Below we report the synthesis of a stable unconventional fullerene derivative C(64)H(4) by introducing methane in the fullerene productions with the normal Krätschmer-Huffman method. We also applied various spectroscopic measurements such as mass spectrometry, (13)C NMR, IR, UV-vis absorption spectrometry, etc. to characterize the structural and electronic properties of this molecule, revealing an unprecedented fullerene cage with a triplet of directly fused pentagons in the framework of C(64)H(4). Four hydrogen atoms are added to the carbons at vertexes of fused pentagons to allow the bond angles at these sites close to the sp(3) tetrahedral angle, which essentially release the sp(2) bond strains on the abutting-pentagon sites of C(64). Ab initio calculations were performed to explore the electronic property and simulate the (13)C NMR and IR spectra of this fulleride, which reproduced well the experimental results and confirmed the structural assignment of the C(64)H(4).

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Scanning tunneling spectroscopy of small Ce-doped endohedral fullerenes on HOPG

Cited by 9 publications

References 30 publications

Electronic phase transition of the valence-fluctuating fulleride Eu2.75C60

Electronic phase transition of the valence-fluctuating fulleride Eu2.75C60

Theoretical study on the smallest endohedral metallofullerenes: TM@C₂₀ (TM = Ce and Gd)

C₆₄H₄: Production, Isolation, and Structural Characterizations of a Stable Unconventional Fulleride

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Scanning tunneling spectroscopy of small Ce-doped endohedral fullerenes on HOPG

Cited by 9 publications

References 30 publications

Electronic phase transition of the valence-fluctuating fulleride Eu2.75C60

Electronic phase transition of the valence-fluctuating fulleride Eu2.75C60

Theoretical study on the smallest endohedral metallofullerenes: TM@C20 (TM = Ce and Gd)

C64H4: Production, Isolation, and Structural Characterizations of a Stable Unconventional Fulleride

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Theoretical study on the smallest endohedral metallofullerenes: TM@C₂₀ (TM = Ce and Gd)

C₆₄H₄: Production, Isolation, and Structural Characterizations of a Stable Unconventional Fulleride