Multiband semimetallic electronic structure of superconducting Ta2PdSe5

We report the electronic structure and related properties of the superconductor Ta2PdSe5 as determined from density functional calculations. The Fermi surface has two disconnected sheets, both derived from bands of primarily chalcogenide p states. These are a corrugated hole cylinder and a heavier complex shaped electron sheet. The sheets contain 0.048 holes and a compensating number of electrons per formula unit, making the material a semimetallic superconductor. The results support the presence of two band superconductivity, although a discrepancy in the specific heat is noted. This discrepancy is discussed as a possible consequence of Pd deficiency in samples.本研究通过密度泛函计算（density functional calculations），报道了超导体Ta₂PdSe₅的电子结构及其相关性质。该体系的费米面（Fermi surface）包含两片互不连通的能带切片，二者均源自主要由硫族化物p轨道态构成的能带：其一为褶皱状空穴（hole）圆柱面，其二为质量更大、形态复杂的电子能带面。每个化学式单元（formula unit）对应的能带片中存在0.048个空穴，以及数量与之补偿的电子，这使得该材料属于半金属超导体。研究结果支持双能带超导机制的存在，但同时观测到比热容（specific heat）数据存在不一致之处。该不一致性被讨论为样品中钯成分缺失的潜在结果。