Superconductivity and topological states in hexagonal TaC and NbC

Li, Xiang-Gui; G., J.; Shi, Lamei; Liu, Peng-Fei; Zhang, Ping; Wang, Bao-Tian

doi:10.1039/d2cp02403a

Cited by 2 publications

(1 citation statement)

References 75 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The literature reports that rocksalt NbC has T c 's of 9 -11 K for bulk phases [68][69][70][71] and 8 -11.5 K for thin films, [72,73] while rocksalt Nb x Zr 1 − x C, or Zr doping in NbC, reduces the T c . [74] However, DFT (density functional theory) simulations suggest that rocksalt and hexagonal NbC may have T c 's as high as 15.7 [75] and 17.1 K, [76] respectively. Also, DFT simulations on the complex NbC 1 − x N x , or nitrogen doping in rocksalt NbC, predict T c 's ranging from 11.2 to 23.1 K, [77] suggesting that the effect of multiple light impurities on the T c is not yet fully understood.…”

Section: Composition Analysis and Open Discussion On The Active Phase...mentioning

confidence: 99%

ZrNb(CO) RF Superconducting Thin Film with High Critical Temperature in the Theoretical Limit

Sun

Oseroff

Baraissov

et al. 2023

Adv Elect Materials

View full text Add to dashboard Cite

Superconducting radio‐frequency (SRF) resonators are critical components for particle accelerator applications, such as free‐electron lasers, and for emerging technologies in quantum computing. Developing advanced materials and their deposition processes to produce RF superconductors that yield nΩ surface resistances is a key metric for the wider adoption of SRF technology. Here, ZrNb(CO) RF superconducting films with high critical temperatures (Tc) achieved for the first time under ambient pressure are reported. The attainment of a Tc near the theoretical limit for this material without applied pressure is promising for its use in practical applications. A range of Tc, likely arising from Zr doping variation, may allow a tunable superconducting coherence length that lowers the sensitivity to material defects when an ultra‐low surface resistance is required. The ZrNb(CO) films are synthesized using a low‐temperature (100 – 200 °C) electrochemical recipe combined with thermal annealing. The phase transformation as a function of annealing temperature and time is optimized by the evaporated Zr‐Nb diffusion couples. Through phase control, one avoids hexagonal Zr phases that are equilibrium‐stable but degrade Tc. X‐ray and electron diffraction combined with photoelectron spectroscopy reveal a system containing cubic β‐ZrNb mixed with rocksalt NbC and low‐dielectric‐loss ZrO2. Proof‐of‐concept RF performance of ZrNb(CO) on an SRF sample test system is demonstrated. BCS resistance trends lower than reference Nb, while quench fields occur at approximately 35 mT. The results demonstrate the potential of ZrNb(CO) thin films for particle accelerators and other SRF applications.

show abstract