Emergence of Kondo Resonance in Graphene Intercalated with Cerium

Hwang, Jinwoong; Kim, Kyoo; Ryu, Hyejin; Kim, Jingul; Lee, Jieun; Kim, Sooran; Kang, Minhee; Park, Byeong‐Gyu; Lanzara, Alessandra; Chung, J. W.; Mo, S.-K.; Denlinger, Jonathan D.; Min, B. I.; Hwang, Choongyu

doi:10.1021/acs.nanolett.8b00784

Cited by 16 publications

(10 citation statements)

References 56 publications

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“…In particular, graphene provides a perfect realization of the pseudogap Kondo problem [35][36][37], when local magnetic moments are created in graphene either by adatom deposition [38][39][40] or via point defects [41][42][43][44][45]. The resulting Kondo physics has attracted much research interest in the last decade [46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61]. Graphene can even realize salient Kondo models with multiple screening channels [62][63][64], having the SU (4) symmetry [65], and exhibiting the super-Ohmic dissipation [66].…”

Section: Introductionmentioning

confidence: 99%

Ferromagnetism-induced Kondo effect in graphene with a magnetic impurity

Fang

Guo

et al. 2019

Phys. Rev. B

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We investigate the many-body effects of a magnetic adatom in ferromagnetic graphene by using the numerical renormalization group method. The nontrivial band dispersion of ferromagnetic graphene gives rise to interesting Kondo physics different from that in conventional ferromagnetic materials. For a half-filled impurity in undoped graphene, the presence of ferromagnetism can bring forth Kondo correlations, yielding two kink structures in the local spectral function near the Fermi energy. When the spin splitting of local occupations is compensated by an external magnetic field, the two Kondo kinks merge into a full Kondo resonance characterizing the fully screened ground state. Strikingly, we find the resulting Kondo temperature monotonically increases with the spin polarization of Dirac electrons, which violates the common sense that ferromagnetic bands are usually detrimental to Kondo correlations. Doped ferromagnetic graphene can behave as half metals, where its density of states at the Fermi energy linearly vanishes for one spin direction but keeps finite for the opposite direction. In this regime, we demonstrate an abnormal Kondo resonance that occurs in the first spin direction, while completely absent in the other one.

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Section: Introductionmentioning

confidence: 99%

Ferromagnetism-induced Kondo effect in graphene with a magnetic impurity

Fang

Guo

et al. 2019

Phys. Rev. B

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“…Different possible symmetries of the impurity orbital and adsorption configurations on the surface of graphene can be modeled by appropriate choices of the matrix elements W j entering Eq. (29). Both experiments and abinitio calculations suggest that two adsorption configurations are energetically most likely: 74 (1) "Top-site" attachment over a single carbon atom, has been observed for Co adatoms on epitaxial monolayer graphene on SiC(0001), as well as for both Co and Ni on quasi-freestanding mononolayer graphene on SiC(0001).…”

Section: A Anderson Impurity Modelmentioning

confidence: 96%

“…Kondo physics has recently been proposed to be the origin of features in angle-resolved photoemission on Ceintercalated graphene. 29 However, the experimental setups most commonly pursued to realize the Kondo effect in graphene involve either vacancies in the carbon lattice or adatoms deposited on top of the sample. Claims of definitive detection of Kondo physics in these settings remain controversial.…”

Section: Introductionmentioning

confidence: 99%

Sublattice symmetry breaking and Kondo-effect enhancement in strained graphene

et al. 2019

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Kondo physics in doped monolayer graphene is predicted to exhibit unusual features due to the linear vanishing of the pristine material's density of states at the Dirac point. Despite several attempts, conclusive experimental observation of the phenomenon remains elusive. One likely obstacle to identification is a very small Kondo temperature scale TK in situations where the chemical potential lies near the Dirac point. We propose tailored mechanical deformations of monolayer graphene as a means of revealing unique fingerprints of the Kondo effect. Inhomogeneous strains are known to produce specific alternating changes in the local density of states (LDOS) away from the Dirac point that signal sublattice symmetry breaking effects. Small LDOS changes can be amplified in an exponential increase or decrease of TK for magnetic impurities attached at different locations. We illustrate this behavior in two deformation geometries: a circular "bubble" and a long fold, both described by Gaussian displacement profiles. We calculate the LDOS changes for modest strains and analyze the relevant Anderson impurity model describing a magnetic atom adsorbed in either a "top-site" or a "hollow-site" configuration. Numerical renormalization-group solutions of the impurity model suggest that higher expected TK values, combined with distinctive spatial patterns under variation of the point of graphene attachment, make the top-site configuration the more promising for experimental observation of signatures of the Kondo effect. The strong strain sensitivity of TK may lift top-site Kondo physics into the range experimentally accessible using local probes such as scanning tunneling microscopy.

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“…The inhomogeneous intercalation results in the electron band structure of both heavily electron-doped graphene by foreign atoms and lightly electron-doped graphene by the SiC substrate, that are electronically coupled each other [13]. Although the lightly electron-doped graphene is influenced by the intercalants, it exhibits similar charge carrier density as pristine graphene, making it possible to investigate the change of electron-electron interaction Phenomena MIT Kondo Magnetism EPC SCs Decorations NO2 [1] Co [3] S [5] AMs [6] Li [7] H [2] Ce [4] Yb [13] TABLE I. A variety of phenomena induced by the decoration of graphene with foreign atoms/molecules.…”

Section: Introductionmentioning

confidence: 99%

Concomitant enhancement of electron-phonon coupling and electron-electron interaction in graphene decorated with ytterbium

Kang

Hwang

Lee

et al. 2019

Applied Surface Science

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The interplay between electron-electron interaction and electron-phonon coupling has been one of the key issues in graphene as it can provide information on the origin of enhanced electron-phonon coupling in graphene by foreign atoms. In ytterbium-decorated graphene on SiC substrate, electronphonon coupling exhibits strong enhancement compared to that of as-grown graphene. Based on angle-resolved photoemission study, the presence of ytterbium is also found to result in the decrease of Fermi velocity, revealing the enhancement of electron-electron interaction within the Fermi liquid theory. Our finding on the concomitant enhancement of electron-electron interaction and electronphonon coupling suggests a possibility of the interplay between the two representative many-body interactions in graphene decorated with foreign atoms.

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Emergence of Kondo Resonance in Graphene Intercalated with Cerium

Cited by 16 publications

References 56 publications

Ferromagnetism-induced Kondo effect in graphene with a magnetic impurity

Ferromagnetism-induced Kondo effect in graphene with a magnetic impurity

Sublattice symmetry breaking and Kondo-effect enhancement in strained graphene

Concomitant enhancement of electron-phonon coupling and electron-electron interaction in graphene decorated with ytterbium

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