Lattice match and charge transfer between distinct block layers (BLs) play an important role in the formation of an intergrowth structure. Herein we propose a simple BL model addressing the different roles of the lattice match and the charge transfer. Inter-BL charge transfer lowers the internal energy, while lattice match minimizes the elastic energy, both of which together make the intergrowth structure stabilized. The model is able to reproduce the lattice parameters precisely for complex iron-based superconductors with intergrowth structures. The elastic energy and the charge-transfer energy are evaluated with assistance of the first-principles calculations. This work rationalizes the basic principles of BL design for intergrowth structures, which can be utilized not only for finding new superconducting materials but also for investigating other layered materials with various functionalities.

No abstract

No abstract

The effect of phosphorus doping in the transition metal germanide Mo5Ge3, which is predicted to be a nodal line semimetal and exhibits superconductivity below Tc = 0.75 K, is studied. It is found that Mo5Ge3−x$_{3-x}$Px retains the tetragonal W5Si3‐type structure up to x = 1.0, and the incorporation of phosphorus leads to a shrinkage of the unit cell volume. Remarkably, Tc of Mo5Ge3−x$_{3-x}$Px is enhanced by more than one order of magnitude with increasing x, reaching 8.24 K at x = 1.0. This enhancement is attributed to the increases in both the density of states at the Fermi level and electron–phonon coupling strength. Theoretical calculations show that the phosphorus doping leads to a nearly rigid‐band shift of the Fermi level into a local maximum of the density of states. This study unveils that transition metal germanides offer an emerging platform to study the interplay between superconductivity and nontrivial band topology.

We report on the synthesis, crystal structure, physical properties, and first-principles calculations of a new borocarbide ThNiBC. The new compound was synthesized by an arc-melting method, crystallizing in a tetragonal LuNiBC-type structure with an exceptionally low axial ratio of c/a = 1.98. The physical property measurements indicate that it is a Pauli-paramagnetic metal with significant electron-electron scattering. Bulk superconductivity at T c = 0.7 K is demonstrated with zero electrical resistivity, Meissner effect, and specific-heat jump. The first-principles calculations reveal a relatively low density of states at the Fermi level with multiple electron-type Fermi surfaces.