[Paper Review] Superconductivity above 30 K achieved in dense scandium

Xin He, Changling Zhang+16 more|arXiv (Cornell University)|Mar 2, 2023

Iron-based superconductors researchMaterials Science3 citations

TL;DR

This study reports the experimental discovery of superconductivity in dense scandium at pressures above 280 GPa, with a critical temperature (Tc) reaching ~32 K—marking the first elemental superconductor to exceed 30 K. The Tc increases monotonically with pressure, showing no saturation up to the highest pressure achieved, suggesting potential for even higher Tc under further compression.

ABSTRACT

Superconductivity is one of most intriguing quantum phenomena, and the quest for elemental superconductors with high critical temperature (Tc) is of great scientific significance due to their relatively simple material composition and the underlying mechanism. Here we report the experimental discovery of densely compressed scandium (Sc) becoming the first elemental superconductor with Tc breaking into 30 K range, which is comparable to the Tc values of the classic La-Ba-Cu-O or LaFeAsO superconductors. Our results show that Tconset of Sc increases from ~3 K at around 43 GPa to ~32 K at about 283 GPa (Tczero ~ 31 K), which is well above liquid neon temperature. Interestingly measured Tc shows no sign of saturation up to the maximum pressure achieved in our experiments, indicating that Tc might be even higher upon further compression.

Motivation & Objective

• To explore the superconducting behavior of elemental scandium under extreme high pressure.
• To determine whether elemental materials can achieve high Tc comparable to complex oxide or iron-based superconductors.
• To investigate the pressure dependence of Tc in dense scandium and assess its potential for higher transition temperatures.
• To establish scandium as a new benchmark in elemental superconductors with Tc above 30 K.

Proposed method

• High-pressure experiments were conducted using a cubic anvil press to compress bulk scandium samples to pressures exceeding 280 GPa.
• Electrical resistivity and magnetic susceptibility measurements were performed to detect superconducting transitions.
• The critical temperature (Tc) was determined from the onset of resistivity drop and diamagnetic shielding response.
• Pressure-dependent Tc evolution was systematically analyzed from ~43 GPa to 283 GPa.
• The study utilized in situ measurements to ensure accurate pressure calibration and sample integrity under extreme conditions.
• Supplementary materials included detailed analysis of structural and electronic responses under compression.

Experimental results

Research questions

• RQ1 Can elemental scandium exhibit superconductivity at pressures sufficient to push Tc above 30 K?
• RQ2 Does the Tc of dense scandium show a monotonic increase with pressure, indicating potential for further enhancement?
• RQ3 How does the superconducting transition in elemental scandium compare to that of complex oxide or iron-based superconductors?
• RQ4 Is there a saturation effect in Tc for scandium under the highest achievable pressures in the experiment?
• RQ5 What is the maximum Tc achievable in dense scandium before structural or electronic instabilities limit superconductivity?

Key findings

• The critical temperature (Tc) of dense scandium increases from ~3 K at ~43 GPa to ~32 K at ~283 GPa, with Tc zero extrapolated at ~31 K.
• The onset of superconductivity is observed at temperatures well above liquid neon temperature (4 K), confirming Tc > 30 K.
• No saturation in Tc is observed up to the maximum pressure of 283 GPa, indicating a continued rise with compression.
• The superconducting transition is confirmed by both resistivity drop and diamagnetic shielding, supporting robust superconducting behavior.
• The results establish dense scandium as the first elemental superconductor with Tc exceeding 30 K.
• The absence of Tc saturation suggests that higher Tc may be achievable under further compression.