Relationship between charge density wave, filamentary superconductivity and bulk superconductivity in ZrTe3

We investigated the relationship between a charge density wave (CDW) with a transition temperature (T-CDW) of similar to 60 K, filamentary superconductivities (SCs) along the a-axis and the b-axis with transition temperatures (T-C's) of similar to 3.5K, and a bulk SC with a T-C below 2.5K in ZrTe3, by measuring electrical resistance and magnetization for several crystals synthesized at different growth temperatures. As the growth temperature increased, the T-CDW decreased, the T-C of the bulk SC increased, and the T-C's of the filamentary SCs did not show a clear change. The anisotropy of the upper critical field (H-C2) was different between the filamentary SCs and the bulk SC. These differences in the growth temperature dependence of T-C and the anisotropy of H-C2 indicate that the filamentary SCs are unrelated to the bulk SC. Moreover, the growth temperature dependence of the transition temperatures indicates that the CDW has a competitive relationship with the bulk SC, but a non-competitive coexistence with the filamentary SCs. Based on the anisotropies of H-C2, we also infer that the filamentary SCs and the bulk SC occur on quasi-one-dimensional Fermi surfaces and a three-dimensional Fermi surface, respectively, and that the relationship between the three states in ZrTe3 cannot be explained solely in terms of conventional competition for a Fermi surface. Copyright (C) 2021 The author(s) Published by the EPLA under the terms of the Creative Commons Attribution 4.0 International License (CC BY).