Mott Insulating Ground State on a Triangular Surface Lattice

Weitering, Hanno H.; Shi, Xiuzhi; Johnson, P. D.; Chen, J.; DiNardo, N. J.; Kempa, Krzysztof

doi:10.1103/physrevlett.78.1331

Cited by 90 publications

(95 citation statements)

References 24 publications

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“…The results show that silicon surface states can have well-defined Fermi surfaces despite a tendency to form localized surface orbitals with correlation gaps [37][38][39]. The metallic states at the Fermi level are well-suited to study low-dimensional electrons because they are decoupled from the bulk in an absolute band gap, and not just in certain k || regions as on metal surfaces.…”

Section: Discussionmentioning

confidence: 98%

Fermi surfaces of surface states on Si(111)-Ag, Au

et al. 2002

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Metallic surface states on semiconducting substrates provide an opportunity to study low-dimensional electrons decoupled from the bulk. Angle resolved photoemission is used to determine the Fermi surface, group velocity, and effective mass for surface states on Si(111)√3×√3-Ag, Si(111)√3×√3-Au, and Si(111)√21×√21-(Ag+Au). For Si(111)√3×√3-Ag the Fermi surface consists of small electron pockets populated by electrons from a few % excess Ag. For Si(111)√21×√21-(Ag+Au) the added Au forms a new, metallic band. The √21×√21 superlattice leads to an intricate surface umklapp pattern and to minigaps of 110 meV, giving an interaction potential of 55 meV for the √21×√21 superlattice.

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Section: Discussionmentioning

confidence: 98%

Fermi surfaces of surface states on Si(111)-Ag, Au

et al. 2002

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“…This has been first interpreted as originating in a Mott metal-insulator transition induced by the reduction of the bandwidth at surface due to the reduction of the effective coordination number [7,8]. The lower and upper Hubbard surface bands have been clearly identify by photoemission and inversephotoemission and the full Mott gap previously established to be roughly 1.5 eV [7]. The new angle resolved photoemission data presented here has been obtained with an energy and momentum resolution one order of magnitude better than in previous works providing additional features.…”

Section: (B)mentioning

confidence: 99%

“…Indeed, the reduction of the bandwidth together with the reduction of screening of the interactions at surface have been shown to lead to a Mott transition implying sp states, the Harrison criterion U/W >> 1 being reached here only at surface. 1/3 K ML/Si(111)-√ 3 × √ 3R30 : B (K/Si:B) has been first proposed to have a Mott-insulator ground state in 1997 [7,8]. Then, such a Mott state at surface has been identified as a generic property of semiconducting surfaces having a √ 3 × √ 3 surface reconstruction [9] i.e.…”

Section: Introductionmentioning

confidence: 99%

“…presenting a triangular pattern such as SiC(0001) [10,11], C/Si(111) [12] and more recently Sn/Ge(111) at low temperature [13]. Moreover, it has been proposed that non-negligible exchange coupling between neighboring dangling bonds electron could lead to the formation of a half-filled frustrated antiferromagnetic triangular network at surface [7,10,15,16] ducting surfaces [17]. Angle-resolved photoemission spectroscopy (ARPES) is known to be a powerful tool since it provides great insights in the nature of the single particle excitation spectra, especially in correlated systems.…”

Section: Introductionmentioning

confidence: 99%

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Novel Bi-Polaronic Ground State in K/Si(111):B

Cárdenas¹,

Fagot‐Revurat²,

Moreau³

et al. 2009

e-J. Surf. Sci. Nanotechnol.

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We report here on low energy electron diffraction (LEED), Auger spectroscopy, scanning tunneling microscopy (STM) and angle-resolved photoemission (ARPES) studies of ultrathin films of K/Si(111)-√ 3 × √ 3R30:B. A potassium-induced surface state is evidenced being maximum at the saturation coverage. ARPES data clearly evidence the folding of the K-induced surface band near the expected kF attesting of a large Mott gap ∆ = 500 meV and a very narrow measured bandwidth W = 140 meV. This clearly signs the strongly correlated nature of this material. Nevertheless, by decreasing the temperature, a novel insulator to insulator surface phase transition is observed characterized by a doubling of the unit cell together with a stabilization of the surface band. In addition, the linear temperature dependence of the ARPES linewidth suggests these materials are characterized by a strong electron-phonon coupling. Therefore, such a phase transition can be explained if the electron-phonon coupling is large enough to compensate the strong on-site repulsion defining a bi-polaronic insulating ground state instead of a Mott-Hubbard one.

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“…Second, the 3 × 3 state still contains an odd electron number/cell, and should be very metallic, while, strikingly, EELS evidence suggests, at least for Pb/Ge(111), a small but finite gap or pseudogap [1]. Much larger and clearer insulating gaps have moreover been recently found on other isoelectronic √ 3 × √ 3 surfaces, such as K/Si(111):B [7], and Si-terminated SiC(0001) [8], where electron counting arguments would similarly predict band metallicity. No structural data are available, however, for K/Si(111):B and SiC(0001).…”

Section: Introductionmentioning

confidence: 99%

First principles calculations of charge and spin density waves of -adsorbates on semiconductors

et al. 1998

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We present ab-initio electronic structure results on the surface of √ 3 × √ 3adsorbates. In particular, we address the issue of metal-insulator instabilities, charge-density-waves (CDWs) or spin-density-waves (SDWs), driven by partly filled surface states and their 2D Fermi surface, and/or by the onset of magnetic instabilities. The focus is both on the newly discovered commensurate CDW transitions in the Pb/Ge(111) and Sn/Ge(111) structures, and on the puzzling semiconducting behavior of the Pb/Ge(111), K/Si(111):B andSiC (0001) surfaces. In all cases, the main factor driving the instability appears to be an extremely narrow surface state band. We have carried out so far preliminary calculations for the Si/Si(111) surface, chosen as our model system, within the gradient corrected local density (LDA+GC) and local spin density (LSD+GC) approximations, with the aim of understanding the possible interplay between 2D Fermi surface and electron correlations in the surface + adsorbate system. Our spin-unrestricted results show that the √ 3 × √ 3 paramagnetic surface is unstable towards a commensurate density wave with periodicity 3 × 3 and magnetization 1/3.

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Mott Insulating Ground State on a Triangular Surface Lattice

Cited by 90 publications

References 24 publications

Fermi surfaces of surface states on Si(111)-Ag, Au

Fermi surfaces of surface states on Si(111)-Ag, Au

Novel Bi-Polaronic Ground State in K/Si(111):B

First principles calculations of charge and spin density waves of -adsorbates on semiconductors

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