Polytypism, polymorphism, and superconductivity in TaSe2−xTex

摘要: Polymorphism in materials often leads to significantly different physical properties—the rutile and anatase polymorphs of TiO2 are a prime example. Polytypism is special type polymorphism, occurring layered when the geometry repeating structural layer maintained but layer-stacking sequence overall crystal structure can be varied; SiC an example material with many polytypes. Although have radically properties, it much rarer for polytypism impact properties dramatic fashion. Here we study effects polymorphism on superconductivity TaSe2, one archetypal members large family dichalcogenides. We show that possible access two stable polytypes TaSe2−xTex solid solution find 3R polytype shows superconducting transition temperature between 6 17 times higher than more commonly found 2H polytype. The reason this change not apparent, propose arises either from remarkable dependence Tc subtle differences characteristics single layers present or surprising effect electronic typically expected dominated by kind.