Superconductivity induced by Ni doping in SmFe(1-x)Ni(x)AsO

Area of Science:

• Condensed Matter Physics
• Materials Science
• Solid-State Chemistry

Background:

• SmFeAsO is a parent compound exhibiting spin-density wave (SDW) order.
• Doping is a common strategy to suppress SDW and induce superconductivity in iron-based superconductors.

Purpose of the Study:

• To investigate the effect of Ni doping on the electronic properties of SmFeAsO.
• To explore the emergence of superconductivity and its correlation with charge carrier behavior.

Main Methods:

• Synthesis of SmFe(1-x)Ni(x)AsO samples with varying Ni content (x).
• Measurements of electrical resistivity, magnetic susceptibility, and thermopower.
• Analysis of the suppression of spin-density wave (SDW) order and the emergence of superconductivity.

Main Results:

• Superconductivity observed for Ni content x ≥ 0.04, with a maximum critical temperature (T(c)) of 10.8 K at x = 0.06.
• Spin-density wave (SDW) order is suppressed by Ni doping.
• Electron-type charge carriers dominate, and thermopower shows anomalous enhancement correlated with superconductivity.
• Upper critical field (H(c2)(0)) estimated at 40 T for the optimally doped sample.

Conclusions:

• Ni doping effectively suppresses SDW order and induces superconductivity in SmFeAsO.
• Anomalous thermopower behavior is linked to the superconducting properties.
• A dome-like phase diagram of T(c)(x) is established, highlighting the interplay between doping, SDW, and superconductivity.