Magnetic-field-independent superconductivity of ultrathin Pb films on cleaved GaAs surface

Sekihara, Takayuki; Masutomi, Ryuichi; Okamoto, Tohru

doi:10.1088/1742-6596/456/1/012034

Cited by 5 publications

(10 citation statements)

References 18 publications

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“…It is known that the 2D superconducting state is extremely vulnerable to quantum phase fluctuations. [ 37,38 ] As a result, the realization of 2D superconductors (based on metals) has remained very difficult and has been achieved only in a few cases. [ 37,39,40 ] We assume that the semiconducting body of zigzag wires could also play a crucial role to support the 2D superconducting surface, similar to the previous observations of superconductivity through low‐dimensional materials supported by semiconducting substrates.…”

Section: Resultsmentioning

confidence: 99%

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Function Follows Form: From Semiconducting to Metallic toward Superconducting PbS Nanowires by Faceting the Crystal

Moayed

Kull

Rieckmann

et al. 2020

Adv Funct Materials

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In the realm of colloidal nanostructures, with their immense capacity for shape and dimensionality control, the form is undoubtedly a driving factor for the tunability of optical and electrical properties in semiconducting or metallic materials. However, influencing the fundamental properties is still challenging and requires sophisticated surface or dimensionality manipulation. Such a modification is presented for the example of colloidal leadsulfide nanowires. It is shown that the electrical properties of lead sulfide nanostructures can be altered from semiconducting to metallic with indications of superconductivity, by exploiting the flexibility of the colloidal synthesis to sculpt the crystal and to form different surface facets. A particular morphology of lead sulfide nanowires is prepared through the formation of {111} surface facets, which shows metallic and superconducting properties in contrast to other forms of this semiconducting crystal, which contain other surface facets ({100} and {110}). This effect, which is investigated with several experimental and theoretical approaches, is attributed to the presence of lead-rich {111} facets. The insights promote new strategies for tuning the properties of crystals and new applications for lead sulfide nanostructures.of materials with different properties. [6,8] One example for the successful implementation of this approach is the synthesis of lead sulfide, which has been produced with a broad spectrum of shapes, sizes, and properties. [10][11][12] This material has been already used for many applications such as photodetectors, [13] field-effect transistors, [14] spintronic components, [2] and solar cells. [15,16] Regarding all of these applications, a certain statement is valid: PbS exhibits semiconducting properties, which is not a surprising fact considering the electronic structure of this material. [2,6,8,[10][11][12][14][15][16][17][18][19][20][21][22] However, violating this statement could be of great scientific and practical importance, since it establishes new strategies to tune the properties of crystalline materials based on their target applications.Here, we introduce a method to change the electrical properties of colloidal lead sulfide nanowires from normal semiconducting to metallic with indications of superconductivity. This could be achieved by faceting the crystal, or in other words, by altering the surface facets of the crystal to the {111} ones, which are single element facets. This Pb-rich surface provides delocalized surface states at room temperature or presumably Cooper pairs at low temperatures, causing metallic and supposedly superconducting properties, in contrast to other forms of PbS nanocrystals, which are all semiconducting. Altering the surface facet is done by ligand-mediated growth in the presence of oleic acid (OA), lithium chloride, and trioctylphosphine, with expressed {111} facets giving a zigzag shape.Such zigzag wires are synthesized together with nanostripes, which have a flat shape, containing Pb and S atoms on their...

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Section: Resultsmentioning

confidence: 99%

“…[ 37,39,40 ] We assume that the semiconducting body of zigzag wires could also play a crucial role to support the 2D superconducting surface, similar to the previous observations of superconductivity through low‐dimensional materials supported by semiconducting substrates. [ 37,38,41 ]…”

Section: Resultsmentioning

confidence: 99%

Function Follows Form: From Semiconducting to Metallic toward Superconducting PbS Nanowires by Faceting the Crystal

Moayed

Kull

Rieckmann

et al. 2020

Adv Funct Materials

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“…However, in a recent report on ultrathin Pb films, a decrease of T c compared to bulk Pb was observed instead, even at a thickness of a few atomic layers only [19]. It is indeed often found that T c is rather suppressed, while the critical field is greatly increased in ultrathin superconducting films [11,19]. This contrasts with the recent observation that the superconducting transition temperature of hollow Pb microspheres [14] was increased from the bulk T c value of 7.2K to 11.0K (1.53 times higher).…”

Section: Introductionmentioning

confidence: 83%

“…Being thin can only cause a minor increase of T c of around 1.05 times exceeding the bulk value [19], while the presence of a curvature [14,15] is able to increase it significantly up to a factor of T c /T c bulk = 1.6. Due to the softer tangential spring components on the curved surface, the electron phonon couplings become larger.…”

Section: Discussionmentioning

confidence: 99%

“…Phonon softening is assumed to be the key element to explain the effective increase of the onset temperature in superconductors of finite size [18]. However, in a recent report on ultrathin Pb films, a decrease of T c compared to bulk Pb was observed instead, even at a thickness of a few atomic layers only [19]. It is indeed often found that T c is rather suppressed, while the critical field is greatly increased in ultrathin superconducting films [11,19].…”

Section: Introductionmentioning

confidence: 99%

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Edge effect and significant increase of the superconducting transition onset temperature of 2D superconductors in flat and curved geometries

Wong

Lortz

2016

Physica C: Superconductivity and its Applications

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In this paper, we present a simple method to model the curvature activated phonon softening in a 2D superconducting layer. The superconducting transition temperature T c in the case of a 2D rectangular sheet, a hollow cylinder and a hollow sphere of one coherence length thickness is calculated by the quantum mechanical electron-phonon scattering matrix, and a series of collective lattice vibrations in the surface state. We will show that being extremely thin in a flat rectangular shape is not enough to significantly enhance the T c through phonon softening. However, if a curvature is added, T c can be strongly enhanced. The increase in T c with respect to the bulk is greatest in a hollow sphere, intermediate in a hollow cylinder and weakest for the rectangular sheet, when systems of identical length scale are considered. In addition, we find that the edge effect of such a 2D sheet has a strong broadening effect on T c in addition to the effect of order parameter phase fluctuations.

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Giant enhancement of superconductivity in arrays of ultrathin gallium and zinc sub-nanowires embedded in zeolite

Zhang

Lyu

Rajan

et al. 2018

Materials Today Physics

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Magnetic-field-independent superconductivity of ultrathin Pb films on cleaved GaAs surface

Cited by 5 publications

References 18 publications

Function Follows Form: From Semiconducting to Metallic toward Superconducting PbS Nanowires by Faceting the Crystal

Function Follows Form: From Semiconducting to Metallic toward Superconducting PbS Nanowires by Faceting the Crystal

Edge effect and significant increase of the superconducting transition onset temperature of 2D superconductors in flat and curved geometries

Giant enhancement of superconductivity in arrays of ultrathin gallium and zinc sub-nanowires embedded in zeolite

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