Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Microwave surface resistance of Tl-1223 films in a dc magnetic field

Alessandro Magalotti, Andrea Alimenti, Emilio Bellingeri, Cristina Bernini, Sergio Calatroni, Alessandro Leveratto, Enrico Silva, Kostiantyn Torokhtii, Ruggero Vaglio, Pablo Vidal García, Nicola Pompeo

TL;DR

This study addresses the microwave surface impedance of Tl-1223 films in dc magnetic fields to assess their suitability as superconducting coatings for the FCC-hh beam screen. It reports two Tl-1223 film batches grown on LaAlO3 via solid-phase epitaxy/PLD, with structural and DC transport characterization to gauge phase purity before microwave testing. Microwave surface impedance was measured with a dielectric-loaded resonator at frequencies $14.9$, $24.2$, and $26.7$ GHz and magnetic fields up to $12$ T, revealing a ~10x reduction in $R_s$ and improved field resilience in the optimized samples. The results support Tl-1223 as a promising high-$T_c$ coating candidate, and future work aims to extract vortex-state parameters for cross-material comparisons, enabling informed assessments against other superconductors for accelerator applications.

Abstract

We present first preliminary surface impedance measurements on Tl-1223 films in dc magnetic fields, in view of potential applications for the next generation Future Circular Collider (FCC-hh) at CERN. The Tl-1223 samples were produced through laser ablation, with nominal thickness of 1 μm and grown on a thick LaAl2O3 substrate. The presence of Tl-1212 phase identified by XRD and BSE microscopy, could be avoided by changing the oxygen partial pressure during heat treatment. The high-frequency transport properties of the samples were characterized using microwave resonant devices, at fixed frequencies of 14.9 GHz, 24.2 GHz and 26.7 GHz, in the temperature range 40 K to 140 K. An external applied static magnetic field up to 12 T was applied. Samples from subsequent batches exhibited huge improvements in the microwave properties, confirming the progress in the deposition technique.

Microwave surface resistance of Tl-1223 films in a dc magnetic field

TL;DR

This study addresses the microwave surface impedance of Tl-1223 films in dc magnetic fields to assess their suitability as superconducting coatings for the FCC-hh beam screen. It reports two Tl-1223 film batches grown on LaAlO3 via solid-phase epitaxy/PLD, with structural and DC transport characterization to gauge phase purity before microwave testing. Microwave surface impedance was measured with a dielectric-loaded resonator at frequencies , , and GHz and magnetic fields up to T, revealing a ~10x reduction in and improved field resilience in the optimized samples. The results support Tl-1223 as a promising high- coating candidate, and future work aims to extract vortex-state parameters for cross-material comparisons, enabling informed assessments against other superconductors for accelerator applications.

Abstract

We present first preliminary surface impedance measurements on Tl-1223 films in dc magnetic fields, in view of potential applications for the next generation Future Circular Collider (FCC-hh) at CERN. The Tl-1223 samples were produced through laser ablation, with nominal thickness of 1 μm and grown on a thick LaAl2O3 substrate. The presence of Tl-1212 phase identified by XRD and BSE microscopy, could be avoided by changing the oxygen partial pressure during heat treatment. The high-frequency transport properties of the samples were characterized using microwave resonant devices, at fixed frequencies of 14.9 GHz, 24.2 GHz and 26.7 GHz, in the temperature range 40 K to 140 K. An external applied static magnetic field up to 12 T was applied. Samples from subsequent batches exhibited huge improvements in the microwave properties, confirming the progress in the deposition technique.
Paper Structure (7 sections, 5 figures)

This paper contains 7 sections, 5 figures.

Table of Contents

  1. Introduction
  2. Samples realization
  3. Film deposition and growth
  4. Structural, morphological and DC transport characterization
  5. Microwave measurements: methods
  6. Results
  7. Conclusion

Figures (5)

  • Figure 1: BSE images of $\text{Tl-1223}$ films grown on LaAlO$_3$ (001). The top panel (Sample I) shows uniform surface coverage by $\text{Tl-1223}$ grains (light gray) together with dark-gray secondary crystals attributed to complex oxide formation. The bottom panel (Sample II) also exhibits good surface coverage, with a noticeably reduced presence of secondary oxides.
  • Figure 2: X-ray diffraction patterns of $\text{Tl-1223}$ films on LaAlO$_3$ (001). The 00l peaks confirm strong c-axis orientation of the $\text{Tl-1223}$ phase. Secondary oxides are marked with stars $\star$, while the Tl-1212 phase, more pronounced in Sample I, is indicated by $\Delta$ (102 and 103 reflections).
  • Figure 3: Resistance vs temperature for $\text{Tl-1223}$ films on LaAlO$_3$ (001). Both samples show sharp superconducting transitions at $\sim$116, due to the $\text{Tl-1223}$ phase.
  • Figure 4: Temperature dependence of $R_s$, with and without a magnetic field. (a) Sample I, ${f=\qty{26.7}{\giga\hertz}}$, ${\mu_0H = \qty{0}{\tesla}}$ and 1.2. (b) Sample II, ${f=\qty{14.9}{\giga\hertz}}$, ${\mu_0H = \qty{0}{\tesla}}$ and 12. Note in Sample I the large residual resistance, the large absolute value of $R_s$ and the strong effect of a moderate magnetic field, and in Sample II the absence of all those effects, with particular attention to the strong magnetic resilience.
  • Figure 5: Field-induced change $\Delta R_s$ at fixed temperatures of 80 and 90 measured at ${f=\qty{26.7}{\giga\hertz}}$ and 24.2 for Sample I and II, respectively.