Polytypism, polymorphism and superconductivity in TaSe2-xTex

Abstract

Polymorphism in materials often leads to significantly different physical properties - the rutile and anatase polymorphs of TiO2 are a prime example. Polytypism is a special type of polymorphism, occurring in layered materials when the geometry of a repeating structural layer is maintained but the layer stacking sequence of the overall crystal structure can be varied; SiC is an example of a material with many polytypes. Although polymorphs can have radically different physical properties, it is much rarer for polytypism to impact physical properties in a dramatic fashion. Here we study the effects of polytypism and polymorphism on the superconductivity of TaSe2, one of the archetypal members of the large family of layered dichalcogenides. We show that it is possible to access 2 stable polytypes and 2 stable polymorphs in the TaSe2-xTex solid solution, and find that the 3R polytype shows a superconducting transition temperature that is nearly 17 times higher than that of the much more commonly found 2H polytype. The reason for this dramatic change is not apparent, but we propose that it arises either from a remarkable dependence of Tc on subtle differences in the characteristics of the single layers present, or from a surprising effect of the layer stacking sequence on electronic properties that instead are expected to be dominated by the properties of a single layer in materials of this kind.

21 pages, 5 figures, 2 tables. A revised version with the same title will appear in PNAS

References in corpus (2)

• A quantum phase transition from triangular to stripe charge order in NbSe${}_2$
• Temperature-dependent Fermi surface of 2H-TaSe2 driven by competing density wave order fluctuations

Cited by in corpus (32)

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• The Commensurate-Incommensurate Charge-Density-Wave Transition and Phonon Zone Folding in 1T-TaSe2 Thin Films
• Polytypism in Few-Layer Gallium Selenide
• Polytypism and Superconductivity in the NbS${}_2$ System
• Polymorphism and superconductivity in the V-Nb-Mo-Al-Ga high-entropy alloys
• Direct Visualization of Trimerized States in 1T'-TaTe${}_2$
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• New polymorphic phase and rich phase diagram in the PdSe2-xTex system
• The Unusual Suppression of Superconducting Transition Temperature in Double-Doping 2H-NbSe${}_2$
• Band structure, superconductivity and polytypism in AuSn${}_4$
• Experimental Evidence of Stable 2$H$ Phase on the Surface of Layered 1$T^{\prime }$-TaTe${}_2$
• Superconductivity in Metal-Rich Chalcogenide Ta2Se
• Optical spectroscopy and ultrafast pump-probe study of structural phase transition in 1T'-TaTe2
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• Topological phase transition in MoTe${}_2$: A Review
• Superconductivity in tantalum self-intercalated 4$Ha$-Ta${}_{1.03}$Se${}_2$
• Unveiling the orbital-selective electronic band reconstruction through the structural phase transition in TaTe${}_2$
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• Identification of a Low Energy Metastable 1$T$-Type Phase for Monolayer VSe2
• Self-doped flat band and spin-triplet superconductivity in monolayer 1T-TaSe${}_{2-x}$Te${}_x$
• Femtosecond trimer quench cycled at megahertz rates in the unconventional charge-density wave material $1\text{T’}-{\text{TaTe}}_2$
• Superconductivity in CuIr2-xAlxTe4 telluride chalcogenides
• Superconducting Sn-Intercalated TaSe${}_2$: Structural Diversity Obscured by Routine Characterization Techniques
• Electronic Landscape of Group-5 Transition Metal Ditellurides $M$Te${}_2$ ($M$ = V, Nb, Ta): Multiple Crystal Phases with Local Bonds and Flat Bands
• Ultrafast optical melting of trimer superstructure in layered 1T'-TaTe2