$\text{Ab Initio}$ Study of Antisite Defects in Nb${}_3$Sn: Phase Diagram and Impact on Superconductivity

Abstract

Antisite defects play a critical role in Nb${}_3$Sn superconducting radio frequency (SRF) cavity physics. Such defects are the primary form of disorder in Nb${}_3$Sn, and are responsible for stoichiometry variations, including experimentally observed tin-depleted regions within grains and tin-rich regions around grain boundaries. But why they cluster to form regions of different stoichiometries and how they affect the SRF properties of Nb${}_3$Sn cavities are not fully understood. Using $\text{ab initio}$ techniques, we calculate the A15 region of the Nb-Sn phase diagram, discuss a possible modification to the phase diagram near grain boundaries, and calculate $T_c$ as a function of stoichiometry, including experimentally inaccessible tin-rich stoichiometry. We find that the impact of antisite defects on the density of states near the Fermi-level of Nb${}_3$Sn plays a key role in determining many of their properties. These results improve our understanding of the obstacles facing Nb${}_3$Sn SRF systems, and how modified growth processes might overcome them.

8 pages, 11 figures

References in corpus (23)

• Maximally-localized generalized Wannier functions for composite energy bands
• Pseudopotentials for high-throughput DFT calculations
• Thermal Contraction and Disordering of the Al(110) Surface
• The Effect of Lattice Vibrations on Substitutional Alloy Thermodynamics
• JDFTx: software for joint density-functional theory
• Ensemble density-functional theory for ab-initio molecular dynamics of metals and finite-temperature insulators
• Advantageous grain boundaries in iron pnictide superconductors
• A Review of the Properties of Nb3Sn and Their Variation with A15 Composition, Morphology and Strain State
• Ab initio phonon coupling and optical response of hot electrons in plasmonic metals
• A review and prospects for Nb3Sn superconductor development
• To use or not to use cool superconductors?
• Superconductivity in the A15 Structure
• Hot carrier dynamics in plasmonic transition metal nitrides
• Superheating field of superconductors within Ginzburg-Landau theory
• Free energy calculation of mechanically unstable but dynamically stabilized bcc titanium
• Theoretical estimates of maximum fields in superconducting resonant radio frequency cavities: Stability theory, disorder, and laminates
• Grain-boundary structure and segregation in Nb3Sn coatings on Nb for high-performance superconducting radiofrequency cavity applications
• Analysis of Nb3Sn surface layers for superconducting RF cavity applications
• Role of surface defects and material inhomogeneities for vortex nucleation in superconductors within time-dependent Ginzburg-Landau theory in 2 and 3 dimensions
• Atomic scale analysis of Nb3Sn on Nb prepared by a vapor-diffusion process for superconducting radiofrequency cavity applications
• Analysis of Magnetic Vortex Dissipation in Sn-Segregated Boundaries in Nb${}_3$Sn Superconducting RF Cavities
• Dynamic transition of vortices into phase slips and generation of vortex-antivortex pairs in thin film Josephson junctions under dc and ac currents
• $\text{Ab Initio}$ Theory of the Impact from Grain Boundaries and Substitutional Defects on Superconducting Nb${}_3$Sn

Cited by in corpus (4)

• Grain-boundary structure and segregation in Nb3Sn coatings on Nb for high-performance superconducting radiofrequency cavity applications
• Smooth, homogeneous, high-purity Nb3Sn superconducting RF resonant cavity by seed-free electrochemical synthesis
• A Time-Dependent Ginzburg-Landau Framework for Sample-Specific Simulation of Superconductors for SRF Applications
• Microscopic Investigation of rf Vortex Nucleation in Nb3Sn Films Using a Near-Field Magnetic Microwave Microscope