Unconventional Bulk Superconductivity in YFe_{2}Ge_{2} Single Crystals

Area of Science:

• Condensed Matter Physics
• Materials Science
• Superconductivity Research

Background:

• YFe2Ge2 exhibits complex electronic properties.
• Previous studies were limited by crystal purity and disorder.

Purpose of the Study:

• Establish bulk superconductivity in high-purity YFe2Ge2.
• Investigate the role of disorder in its superconducting state.
• Enable advanced multiprobe experiments.

Main Methods:

• Growth of high-purity YFe2Ge2 single crystals using a novel liquid transport technique.
• Low-temperature heat capacity measurements.
• Analysis of residual resistivity and superconducting transition anomalies.

Main Results:

• Demonstrated intrinsic bulk superconductivity in YFe2Ge2.
• Observed disorder and field-dependent Sommerfeld coefficient.
• Achieved a sevenfold reduction in disorder scattering, reaching residual resistivities of approximately 0.45 μΩ cm.
• Identified evidence for disorder-induced in-gap states.

Conclusions:

• High-purity YFe2Ge2 exhibits intrinsic bulk superconductivity.
• The superconducting order parameter is likely sign-changing, influenced by disorder.
• The new crystal growth method facilitates future investigations into the normal and superconducting states of YFe2Ge2.