Superconductivity and disorder effect in TlNi2Se(2-x)S(x) compounds

Area of Science:

• Condensed Matter Physics
• Materials Science

Background:

• Multi-band superconductivity (SC) was previously discovered in TlNi2Se2.
• The TlNi2Se(2-x)S(x) system offers a new avenue to explore SC by substituting sulfur for selenium.

Purpose of the Study:

• To synthesize and characterize TlNi2Se(2-x)S(x) single crystals.
• To investigate the impact of sulfur substitution and disorder on superconductivity and heavy-electron behavior.

Main Methods:

• Synthesis of TlNi2Se(2-x)S(x) single crystals (0.0 ≤ x ≤ 2.0).
• Measurements of resistivity, specific heat, and magnetic susceptibility.
• Analysis of normal state electronic specific heat and upper critical field (H(C2)(T)).

Main Results:

• Superconductivity (T(C) = 2.3 K) and heavy-electron behavior (m* = 13-25 m(b)) observed in TlNi2S2.
• Bulk SC and heavy-electron behavior are maintained in all TlNi2Se(2-x)S(x) samples.
• A novel change in the field dependence of the residual specific heat coefficient (γ(N)(H)) was observed with increasing sulfur content.
• Superconducting transition temperature (T(C)) varies with disorder, indicated by the residual resistivity ratio (RRR).

Conclusions:

• The TlNi2Se(2-x)S(x) system serves as a valuable platform for studying disorder effects on multi-band superconductivity.
• Partial substitution of sulfur for selenium preserves key superconducting and heavy-electron properties.
• Disorder plays a significant role in modulating the superconducting properties of this material system.