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Polytypism, polymorphism, and superconductivity in TaSe 2 −x Te x

Author(s): Luo, Huixia; Xie, Weiwei; Tao, Jing; Inoue, Hiroyuki; Gyenis, András; et al

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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 two stable polytypes and two stable polymorphs in the TaSe2−xTex solid solution and find that the 3R polytype shows a superconducting transition temperature that is between 6 and 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 are typically expected to be dominated by the properties of a single layer in materials of this kind.
Publication Date: 17-Mar-2015
Electronic Publication Date: 3-Mar-2015
Citation: Luo, Huixia, Xie, Weiwei, Tao, Jing, Inoue, Hiroyuki, Gyenis, András, Krizan, Jason W., Yazdani, Ali, Zhu, Yimei, Cava, Robert Joseph. (2015). Polytypism, polymorphism, and superconductivity in TaSe 2 −x Te x. Proceedings of the National Academy of Sciences, 112 (11), E1174 - E1180. doi:10.1073/pnas.1502460112
DOI: doi:10.1073/pnas.1502460112
ISSN: 0027-8424
EISSN: 1091-6490
Pages: E1174 - E1180
Type of Material: Journal Article
Journal/Proceeding Title: Proceedings of the National Academy of Sciences
Version: Final published version. Article is made available in OAR by the publisher's permission or policy.

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