[论文解读] Reversible tuning of superconductivity in pressurized qausi-one-dimensional A2Cr3As3 (A=K and Rb)

Zhe Wang, Vladimir Sidorov+11 more|arXiv (Cornell University)|Feb 15, 2015

Iron-based superconductors research参考文献 5被引用 5

一句话总结

本研究 investigates reversible suppression of superconductivity in quasi-one-dimensional A2Cr3As3 (A=K, Rb) under hydrostatic and uniaxial pressure. It demonstrates that both pressure types reduce Tc, with uniaxial pressure being more effective, and that Tc fully recovers upon pressure release, indicating elastic lattice tuning. The Cr–Cr bond distance and angle in Cr3As3 chains are identified as key structural parameters governing Tc, with pristine K2Cr3As3 exhibiting optimal superconducting properties.

ABSTRACT

In-situ hydrostatic and uniaxial high pressure studies were performed on recently discovered CrAs-based qausi-one-dimensional superconductors A2Cr3As3 (A=K and Rb). The established Pressure-Temperature phase diagram in this study clearly demonstrates that either hydrostatic pressure or uniaxial pressure globally suppresses the superconducting transition temperature (Tc), and the latter is more effective than the former. Interestingly, in the same hydrostatic pressure environment, the suppressing rate of Tc in Rb2Cr3As3 is nearly twice as that of K2Cr3As3. Significantly, the reduced Tc in these superconductors can fully recover to its ambient-pressure value after the applied pressure is entirely released. Our results suggest that the bonding distance and angle between Cr-Cr in the Cr3As3 chains are the key factor in determining Tc and that the optimal lattice for superconductivity is hosted in the pristine K2Cr3As3.

研究动机与目标

• To investigate the pressure-dependent behavior of superconducting transition temperature (Tc) in quasi-one-dimensional A2Cr3As3 (A=K, Rb).
• To compare the effects of hydrostatic versus uniaxial pressure on Tc suppression.
• To determine whether Tc suppression is reversible upon pressure release.
• To identify structural parameters—specifically Cr–Cr bond distance and angle—that govern superconducting properties.

提出的方法

• In-situ hydrostatic high-pressure measurements were performed using a cubic anvil press with resistivity and magnetic susceptibility techniques.
• Uniaxial pressure was applied using a custom-designed anvil system to probe anisotropic lattice effects.
• Pressure-dependent resistivity and magnetic susceptibility were measured to track Tc evolution.
• The pressure-Tc phase diagrams were constructed for both K2Cr3As3 and Rb2Cr3As3 under varying pressure conditions.
• Structural parameters (Cr–Cr distance and angle) were correlated with Tc suppression rates.
• Reversibility of Tc was tested by fully releasing pressure and measuring recovery to ambient Tc.

实验结果

研究问题

• RQ1 How does hydrostatic pressure affect the superconducting transition temperature (Tc) in K2Cr3As3 and Rb2Cr3As3?
• RQ2 To what extent is uniaxial pressure more effective than hydrostatic pressure in suppressing Tc?
• RQ3 Is the suppression of Tc under pressure reversible upon release of pressure?
• RQ4 What structural parameters in the Cr3As3 chains govern the magnitude of Tc suppression?
• RQ5 Why is the Tc suppression rate in Rb2Cr3As3 nearly twice that of K2Cr3As3 under the same hydrostatic pressure?

主要发现

• Uniaxial pressure suppresses Tc more effectively than hydrostatic pressure in both K2Cr3As3 and Rb2Cr3As3.
• Under identical hydrostatic pressure, Tc in Rb2Cr3As3 is suppressed at nearly twice the rate of K2Cr3As3.
• Tc fully recovers to its ambient-pressure value after complete release of pressure, indicating reversible, elastic lattice tuning.
• The Cr–Cr bond distance and bond angle in the Cr3As3 chains are identified as the primary structural factors controlling Tc.
• Pristine K2Cr3As3 hosts the optimal lattice configuration for superconductivity, as it exhibits the slowest Tc suppression rate.
• The results suggest that superconductivity in these materials is highly sensitive to lattice distortions, particularly in the Cr3As3 chain geometry.