Site-Specific Kondo Effect at Ambient Temperatures in Iron-Based Molecules

Gao, Li; Ji, Wei; Hu, Yong‐Sheng; Cheng, Zhihai; Deng, Zanhong; Liu, Q.; Jiang, Nan; Lin, Xiuping; Guo, Wei; Du, Shixuan; Hofer, Werner A.; Xie, Xiaoming; Gao, Hongjun

doi:10.1103/physrevlett.99.106402

Cited by 255 publications

(202 citation statements)

References 41 publications

Supporting

Mentioning

182

Contrasting

Order By: Relevance

“…8,13 Calculations of the free and adsorbed molecule envisage significant a 1g hole contribution, in contrast with the orbital occupancy found here. Further, DFT predicts a strong change of the Fe electron valence upon adsorption, which is not supported by our measurements.…”

contrasting

confidence: 52%

“…12 Conversely, the weak mixing between d 6 E and d 7 found for FePc/Au(111) shows that this system belongs to the local moment Kondo regime, in accord with local conductance measurements by STM. 8 The reduced S = 1/2 effective spin of the FePc/Au(111) complex suggests that the Fermi level resonance observed by STM at 5 K (Ref. 8) may be due to partial screening of the S = 1 spin of FePc, that is, to a manifestation of the underscreened Kondo effect.…”

mentioning

confidence: 99%

“…The model assumes a Co d 7 configuration with an additional electron in a separate orbital that can hop to the Co ion, thereby creating a d 8 In general, covalency of metal ions in oxides and metalorganic complexes is modeled by configurational mixing with a filled ligand shell as d n + d n+1 L −1 , where L −1 denotes a ligand hole. 1,15 In this way, the total number of electrons of the TM complex is equal to that of the free molecule.…”

mentioning

confidence: 99%

“…[2][3][4]8,9 Yet, due to the difficulty of modeling exchange and electron correlation phenomena using effective one-electron potentials, DFT affords only a partial description of the magnetic properties of TM complexes. 1 Methods beyond standard DFT that include Coulomb repulsion through semiempirical Hubbard U terms have been successfully employed to describe the ground state of isolated molecules.…”

mentioning

confidence: 99%

See 3 more Smart Citations

Mixed-valence behavior and strong correlation effects of metal phthalocyanines adsorbed on metals

et al. 2011

View full text Add to dashboard Cite

We investigate the hierarchy of local correlation and hybridization effects in metal-organic molecules adsorbed on metals. Using x-ray magnetic circular dichroism and ligand field multiplet calculations, we demonstrate that the 3d electronic ground state of monolayer metal-phthalocyanine (CoPc, FePc) on Au (111) is given by the coherent superposition of two charge states, d n E + d n+1 , where E represents a substrate electron antiferromagnetically coupled to the central metal ion and d n the many-body ionic orbital configuration of the unperturbed molecule. These results differ from previous models of hybrid metal-organic systems and provide a consistent description of their magnetic moments and Kondo physics in terms of spin and orbital multiplicity. The magnetic properties of transition-metal (TM) compounds depend critically on the competition between d-d electron correlation and covalency, that is, the transfer of charge between d-orbitals and delocalized ligand states. 1 Charge transfer (CT) affects the magnetization of TM ions, their coupling through indirect exchange paths, as well as the conductivity of important classes of materials, including TM oxides, high-T c superconductors, and molecular complexes. Recently, CT processes that take place at the interface between magnetic molecules and metal surfaces have come under intensive attention. 2-4 Transport measurements of single molecules trapped between metallic electrodes 5 and layered metal/organic heterostructures 6 have revealed the role played by interfacial hybridization in determining efficient charge and spin injection across TM complexes, a prerequisite to developing molecular spintronic devices. 6,7 A comprehensive description of the electronic and magnetic properties of metal-organic hybrids, however, is complicated by the fact that CT can occur between TM and ligand orbitals, but also between any of these states and the electron reservoir of a supporting metal surface or electrode. Clearly, understanding such processes would be of great importance in modeling and controlling the properties of magnetic molecules interfaced with metals.Density functional theory (DFT) provides the basis of our current understanding of hybrid metal-organic systems. [2][3][4]8,9 Yet, due to the difficulty of modeling exchange and electron correlation phenomena using effective one-electron potentials, DFT affords only a partial description of the magnetic properties of TM complexes. 1 Methods beyond standard DFT that include Coulomb repulsion through semiempirical Hubbard U terms have been successfully employed to describe the ground state of isolated molecules. 10 However, DFT + U remains a mean-field scheme, which precludes a proper modeling of valence and spin fluctuations induced by CT.A notable case where CT has a dramatic influence on the magnetism of a TM complex is that of Co-phthalocyanine (CoPc), a well-known molecule with spin S = 1/2 (Ref. 11).DFT predicts that CoPc adsorbed on Au(111) (Refs. 12 and 13), Cu (111) (Ref. 14), and even ferromagnetic Fe(110...

show abstract

contrasting

confidence: 52%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Mixed-valence behavior and strong correlation effects of metal phthalocyanines adsorbed on metals

et al. 2011

View full text Add to dashboard Cite

show abstract

“…Negligible hybridization of the d x2-y2 orbital with the substrate hinders charge transfer towards either Cu or Ni atoms, preserving the spin of the central metal ions 12 . This is in contrast to molecules that include Mn, Fe, and Co ions, where empty d-orbitals projecting outside the molecular plane directly hybridize with the substrate, leading to either quenching [13][14][15][16][17] or Kondo screening 18,19 of the metal spin.…”

Section: Pristine Spin Moment and Adsorption Of Cupc And Nipc On Ag(1mentioning

confidence: 99%

Spin coupling and relaxation inside molecule–metal contacts

et al. 2011

View full text Add to dashboard Cite

Advances in molecular electronics depend on the ability to control the charge and spin of single molecules at the interface with a metal. Here we show that bonding of metal-organic complexes to a metallic substrate induces the formation of coupled metal-ligand spin states, increasing the spin degeneracy of the molecules and opening multiple spin relaxation channels. scanning tunnelling spectroscopy reveals the sign and magnitude of intramolecular exchange coupling as well as the orbital character of the spin-polarized molecular states. We observe coexisting Kondo, spin, and vibrational inelastic channels in a single molecule, which lead to pronounced intramolecular variations of the conductance and spin dynamics. The spin degeneracy of the molecules can be controlled by artificially fabricating molecular clusters of different size and shape. By comparing data for vibronic and spin-exchange excitations, we provide a positive test of the universal scaling properties of inelastic Kondo processes having different physical origin.

show abstract