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Ultrathin Magnesium-Based Coating as an Efficient Oxygen Barrier for Superconducting Circuit Materials

Journal Article · · Advanced Materials
 [1];  [1];  [2];  [3];  [4];  [5];  [6];  [1];  [1];  [1];  [1];  [7];  [3];  [3];  [2];  [8];  [4];  [1]
  1. Brookhaven National Laboratory (BNL), Upton, NY (United States). Center for Functional Nanomaterials (CFN)
  2. Brookhaven National Laboratory (BNL), Upton, NY (United States); Stony Brook Univ., NY (United States)
  3. Brookhaven National Laboratory (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II)
  4. Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
  5. Princeton Univ., NJ (United States)
  6. Brookhaven National Laboratory (BNL), Upton, NY (United States). Center for Functional Nanomaterials (CFN); Stony Brook Univ., NY (United States)
  7. National Institute of Standard and Technology, Gaithersburg, MD (United States). Material Measurement Laboratory
  8. Brookhaven National Laboratory (BNL), Upton, NY (United States)
+ Show Author Affiliations

Scaling up superconducting quantum circuits based on transmon qubits necessitates substantial enhancements in qubit coherence time. Over recent years, tantalum (Ta) has emerged as a promising candidate for transmon qubits, surpassing conventional counterparts in terms of coherence time. However, amorphous surface Ta oxide layer may introduce dielectric loss, ultimately placing a limit on the coherence time. In this study, a novel approach for suppressing the formation of tantalum oxide using an ultrathin magnesium (Mg) capping layer is presented. Synchrotron-based X-ray photoelectron spectroscopy studies demonstrate that oxide is confined to an extremely thin region directly beneath the Mg/Ta interface. Additionally, it is demonstrated that the superconducting properties of thin Ta films are improved following the Mg capping, exhibiting sharper and higher-temperature transitions to superconductive and magnetically ordered states. Moreover, an atomic-scale mechanistic understanding of the role of the capping layer in protecting Ta from oxidation is established based on computational modeling. Further, this work provides valuable insights into the formation mechanism and functionality of surface tantalum oxide, as well as a new materials design principle with the potential to reduce dielectric loss in superconducting quantum materials. Ultimately, the findings pave the way for the realization of large-scale, high-performance quantum computing systems.

Research Organization:
Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Brookhaven National Laboratory (BNL), Upton, NY (United States). Center for Functional Nanomaterials (CFN); Brookhaven National Laboratory (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE)
Grant/Contract Number:
AC05-76RL01830; SC0012704; AC02-05CH11231
OSTI ID:
2316006
Alternate ID(s):
OSTI ID: 2324577
Report Number(s):
PNNL-SA--194072
Journal Information:
Advanced Materials, Journal Name: Advanced Materials Vol. 23; ISSN 0935-9648
Publisher:
WileyCopyright Statement
Country of Publication:
United States
Language:
English

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Related Subjects

36 MATERIALS SCIENCE
capping layer
superconducting qubits
surface oxide
tantalum thin film