Structural study of the close-packed two-dimensional phases of Pb on Ge(111) and Si(111)

Seehofer, L.; Falkenberg, Gerald; Daboul, D.; Johnson, R.L.

doi:10.1103/physrevb.51.13503

Cited by 99 publications

(69 citation statements)

References 33 publications

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“…Moreover, the ( √ 3× √ 3) spots reveal a threefold splitting [enlarged in Fig. 1(e)] that is due to the formation superstructures with appearance of both H3 and T4 centered local reconstructions, which are separated by quasi-( √ 7× √ 3)-domain walls [39,40] as also visible in STM [ Fig. 1(a); the (13× √ 3) superstructure with 1.308 ML coverage is shown in Fig.…”

Section: A Atomic Structure Of the Sic Phasementioning

confidence: 99%

Spin-resolved band structure of a densely packed Pb monolayer on Si(111)

et al. 2017

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Monolayer structures of Pb on Si(111) attracted recently considerable interest as superconductivity was found in these truly two-dimensional (2D) structures. In this study, we analyzed the electronic surface band structure of the so-called striped incommensurate Pb phase with 4 3 ML coverage by means of spin-resolved photoemission spectroscopy. Our results fully agree with density functional theory calculations done by Ren et al. [Phys. Rev. B 94, 075436 (2016)]. We observe a local Zeeman-type splitting of a fully occupied and spin-polarized surface band at the K √ 3 points. The growth of this densely packed Pb structure results in the formation of imbalanced rotational domains, which triggered the detection of C 3v symmetry forbidden spin components for surface states around the Fermi energy. Moreover, the Fermi surface of the metallic surface state of this phase is Rashba spin split and revealed a pronounced warping. However, the 2D nesting vectors are incommensurate with the atomic structure, thus keeping this system rather immune against charge density wave formation and possibly enabling a superconducting behavior.

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Section: A Atomic Structure Of the Sic Phasementioning

confidence: 99%

Spin-resolved band structure of a densely packed Pb monolayer on Si(111)

et al. 2017

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“…The striped incommensurate (SIC) phase of the Pb-Si surface shown in Fig. 1(a) was prepared by deposition of ~ 1ML of Pb onto the Si(111) 7 7 × surface at room temperature, followed by sample annealing at 400 ~ 450 o C for 4 min to form the surface template [22][23][24] . Depending on the detailed kinetic control, either flat film or 2-d nanoislands of Pb can be obtained.…”

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Universal quenching of the superconducting state of two-dimensional nanosize Pb-island structures

et al. 2011

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We systematically address superconductivity of Pb nano-islands with different thicknesses and lateral sizes via a scanning tunneling microscopy/spectroscopy. Reduction of the superconducting gap (Δ) is observed even when the island is larger than the bulk coherence length (ξ) and becomes very fast below ~ 50 nm lateral size. The suppression of Δ with size depends to a good approximation only on the volume of the island and is independent of its shape. Theoretical analysis indicates that the universal quenching behavior is primarily manifested by the mean number of electronic orbitals within the pairing energy window. 2The remarkable properties of a superconductor are due to its Cooper pair condensate (formed from a macroscopic number of electrons), which can be described by a single quantum wave function. According to the celebrated Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity 1 , there is a minimum length scale (the coherence length, ξ) on which the condensate order parameter can vary. The fate of superconductivity in systems with spatial dimensions smaller than the coherence length, ξ, has been the subject of intense interest for decades because it is dependent on quantum confinement, interaction, and quantum coherence effects in an intrinsically many-particle context--ingredients that drive much modern research in quantum many-body physics [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] . Attention has often focused on two-dimensional (2-d) systems which can have fragile order because of quantum and thermal fluctuations. In this context, the recent discovery of robust superconductivity in epitaxial thin Pb films with thicknesses that are orders of magnitude smaller than ξ seems surprising 4,10,11 . Even at a thickness of only two atomic layers (~ 0.6 nm), the superconducting transition temperature (T C ~ 5 K) of Pb films is only slightly smaller than the bulk value 7.2 K 4 . Nevertheless, there remain disputes regarding the thickness dependence of T C at thickness below 10 MLs. Although this observation is already interesting, much more telling information on the fate of superconductivity at small length scales emerges when the lateral dimensions of the ultra-thin films are also reduced. The experiments were conducted in a home-built low temperature STM system with an in-situ sample preparation chamber. The striped incommensurate (SIC) phase of the Pb-Si surface shown in Fig. 1 , where a and b are lengths along the major and minor axes, respectively. Recently Brun et al. 15 reported a study of thickness dependence of the superconducting gap of Pb 2-d islands with lateral size larger than ξ which they interpreted to represent the superconducting properties of extended films. They found that the superconducting gap scales with the inverse of island thickness and superconductivity should vanish at a thickness of 2 ML.While the recent observation of strong superconductivity at 2ML already implied the breakdown of the 1/d scaling 4 , the current result that gap reduc...

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“…being the stable phase at 6/5 ML and T<270K. It is still not clear what the high temperature phase for T>270K and the nature of the phase transition is, whether it is the HIC [12] or the disordered (1x1) phase[l5]. In addition, in the range of 1/3 < 8 < 6/5 ML, experimentally there is coexistence between the 1/3 ML 3 x 3 phase and the fi x fi phase at low temperature.…”

Section: 1mentioning

confidence: 99%

Theoretical Studies of Pb on Si(111) and Si(100), Global Search for H-Passivated Si Nanowires, and Construction of highly Localized Quasiatomic Minimal Basis Orbitals for Mo

Chan

2005

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Structural study of the close-packed two-dimensional phases of Pb on Ge(111) and Si(111)

Cited by 99 publications

References 33 publications

Spin-resolved band structure of a densely packed Pb monolayer on Si(111)

Spin-resolved band structure of a densely packed Pb monolayer on Si(111)

Universal quenching of the superconducting state of two-dimensional nanosize Pb-island structures

Theoretical Studies of Pb on Si(111) and Si(100), Global Search for H-Passivated Si Nanowires, and Construction of highly Localized Quasiatomic Minimal Basis Orbitals for Mo

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