Non-Fermi-Liquid Behavior of Superconducting SnH₄

Area of Science:

• Materials Science
• Condensed Matter Physics
• Superconductivity Research

Background:

• High-pressure synthesis is crucial for discovering novel materials with unique properties.
• Superhydrides, compounds with a high hydrogen content, are of great interest due to their potential for high-temperature superconductivity.
• Understanding the behavior of materials under extreme pressure provides insights into fundamental physics.

Purpose of the Study:

• To investigate the chemical interaction of tin (Sn) with hydrogen (H2) under high pressures.
• To synthesize and characterize new tin hydride phases.
• To explore the superconducting properties and magnetic field behavior of the synthesized SnH4.

Main Methods:

• X-ray diffraction (XRD) was employed to study the crystal structure of tin hydrides formed at high pressures (180-210 GPa).
• Electrical resistance and critical current density (Jc) measurements were conducted to determine superconducting properties.
• Magnetoresistance and upper critical magnetic field (Bc2) were measured to understand behavior in magnetic fields.

Main Results:

• A novel cubic (fcc) tin tetrahydride (SnH4) was synthesized, exhibiting superconductivity with a critical temperature (Tc) of 72 K at 180 GPa.
• Formation of other tin hydrides, including a superhydride (C2/m-SnH14), was detected.
• The superconducting gap in SnH4 was determined to be 2Δ(0) = 21.6 meV.
• SnH4 displayed anomalous behavior in magnetic fields, including linear magnetoresistance and Bc2(T) ∝ (Tc - T), deviating from conventional superconductor models.
• Electrical resistance in the non-superconducting state showed deviations from the Bloch-Grüneisen model, suggesting physics beyond Fermi liquid theory.

Conclusions:

• The discovery of superconducting SnH4 at 72 K under high pressure is a significant advancement in hydride superconductivity research.
• The unusual magnetic field response and electrical transport properties of SnH4 challenge existing theories for conventional superconductors.
• These anomalies align SnH4 and other superhydrides more closely with complex materials like cuprates, indicating a need for new theoretical frameworks.