Magnetic field screening in hydrogen-rich high-temperature superconductors

Area of Science:

• Condensed Matter Physics
• Materials Science
• High-Pressure Science

Background:

• Hydrogen-rich compounds exhibit high superconducting transition temperatures (T_c), approaching room temperature.
• Extreme pressures (over 1 million atmospheres) limit experimental studies and understanding of these hydrides.
• Magnetic properties of high-temperature superconducting hydrides remain underexplored compared to electrical transport measurements.

Purpose of the Study:

• To characterize the magnetic properties of high-temperature superconducting hydrides under extreme pressure.
• To determine key superconducting parameters, including lower critical field (H_c1) and London penetration depth (λ_L).
• To classify the type of superconductivity (e.g., type I, type II) in H₃S and LaH₁₀.

Main Methods:

• Development and application of SQUID magnetometry under extreme high-pressure conditions.
• Investigated Im-3m-H₃S and Fm-3m-LaH₁₀, representative high-temperature superconducting hydrides.
• Measured superconducting parameters such as lower critical field and London penetration depth.

Main Results:

• Determined lower critical fields (H_c1) of ~0.82 T for H₃S and ~0.55 T for LaH₁₀.
• Measured London penetration depths (λ_L) of ~20 nm for H₃S and ~30 nm for LaH₁₀, indicating high superfluid density.
• Calculated Ginzburg-Landau parameters (κ) of ~12-20, classifying them as moderate type II superconductors.

Conclusions:

• H₃S and LaH₁₀ exhibit moderate type II superconductivity, contrary to expectations for high T_c materials.
• The study provides crucial magnetic characterization for understanding high-temperature superconductivity in hydrides.
• Advanced high-pressure SQUID magnetometry enables detailed investigation of exotic superconducting materials.