arXiv subjects

Shuaihang Sun

Publications and source records attributed to Shuaihang Sun.

4 recordsLinked to original sources

arXiv2026

Different reconstruction pathways toward superconductivity in TaRhTe4 and TaIrTe4 Weyl semimetals

Pressure can drive Weyl semimetals toward superconductivity through qualitatively distinct reconstructions of their lattices and normal-state electronic structures. Here, we report the first observation of superconductivity in compressed TaRhTe4. This finding enables a direct comparison of the distinct reconstruction pathways leading to superconductivity in TaRhTe4 and the previously studied TaIrTe4, both of which belong to the TaXTe4 (X = Rh, Ir) family of type-II Weyl semimetals. For TaRhTe4, high-pressure electrical-resistance, Hall effect, and magnetoresistance measurements, together with synchrotron X-ray diffraction and first-principles calculations, reveal a superconducting transition that emerges near 20 GPa, with onset Tc increasing to approximately 2.6 K at 65.2 GPa and zero resistance achieved above 63 GPa. The onset of superconductivity coincides with a progressive lattice distortion, a strong suppression of the positive magnetoresistance, and a continuous decrease of the Hall coefficient toward zero. Calculations further show that additional electron-like bands cross the Fermi level (EF) and that N(EF) increases upon compression. This evolution contrasts with TaIrTe4, where the Hall coefficient initially increases before reversing its pressure dependence near the superconducting threshold, while the structural anomaly is confined to a narrower pressure interval. This comparison indicates that superconductivity in the TaXTe4 family is not tied to a unique critical pressure or a single Fermi-surface reconstruction, but can emerge through distinct material-specific pathways once pressure sufficiently reconstructs the low-carrier Weyl-semimetal-derived state into a multiband metallic regime.

cond-mat.supr-con↗

arXiv2026

Enhanced and robust superconductivity in La0.8Sr0.2NiO2 membranes compressed up to 210 GPa

The discovery of superconductivity in infinite-layer nickelate thin films has opened a new frontier for exploring unconventional oxide superconductors beyond the copper oxide family. However, the presence of substrate hampers investigations under very high pressure. Recently, this problem was circumvented by a study of freestanding Nd0.85Sr0.15NiO2 membranes, which revealed that superconducting transition temperature kept increasing as the pressure was ramped up to 91 GPa, without showing signs of saturation. Naturally, one wonders what would happen at even higher pressures. Here, we report that superconductivity in a freestanding La0.8Sr0.2NiO2 membrane persists under applied ultrahigh pressures up to 210 GPa. The superconducting transition onset temperature exhibits a continuous dome-like evolution, increasing from 16 K at ambient pressure to a peak of 74.5 K at 146 GPa, and then gradually decreasing to 57.4 K at 210 GPa. Such robustness of superconductivity against ultrahigh pressure has not been observed in high-Tc oxide superconductors before.

cond-mat.supr-con↗

arXiv2026

Pressure-enhanced superconductivity and its correlation with suppressed resistance dip in (La,Pr)3Ni2O7 films

The discovery of superconductivity with a transition temperature (Tc) exceeding 40 K in La3Ni2O7 and (La,Pr)3Ni2O7 thin films at ambient pressure provides a viable platform for the experiments that can only be conducted under ambient-pressure conditions, and for the theoretical investigations aimed at understanding the commonalities and peculiarities of the behaviors related to the superconductivity between the film and the compressed bulk systems - including the effects of oxygen vacancies and strain. Consequently, it is crucial to determine whether Tc can be further enhanced and to uncover the underlying physics that controls the Tc value in these ambient-pressure superconducting thin films. Here, we report a systematic study of hydrostatic pressure effects on the superconducting properties of (La,Pr)3Ni2O7 thin films. We find that external pressure universally enhances Tc of the film samples regardless of their initial Tc value. The onset Tc of 68.5 K at 2.0 GPa demonstrates a notable increase from 62 K at 0.3 GPa. Furthermore, we observe that the samples without zero resistance show a resistance dip just above the superconducting transition, whereas the samples that exhibit zero resistance do not display this dip. Applying pressure can suppress the dips and drive the system toward zero resistance. Based on our results, we propose that this feature is associated with oxygen vacancies and that the depth of the dip can serve as an indicator of the concentration of the vacancies. It is plausible that the dip is caused by the localization of mobile electrons at the vacancy sites. Applying pressure can delocalize these electrons, which in turn may contribute to the increase in Tc.

cond-mat.supr-con↗

arXiv2025

Signatures of a Lifshitz transition in pressurized electron-doped cuprate

It is well known that the electronic structure of hole-doped cuprate superconductors is tunable through both chemical doping and external pressure, which frequently offer us new insights of understanding on the high-Tc superconducting mechanism. While, for electron-doped cuprate superconductors, although the chemical doping effects have been systematically and thoroughly investigated, there is still a notable lack of experimental evidence regarding the pressure-driven coevolution of Tc and electronic structure. In this study, we report the first observation on the signatures of pressure-induced Lifshitz transition in Pr0.87LaCe0.13CuO4+delta (PLCCO) single crystal, a typical electron-doped cuprate superconductor, through the comprehensive high-pressure measurements of electrical resistance, Hall coefficient (RH) and synchrotron X-ray diffraction (XRD). Our results reveal that, at 40 K, the ambient-pressure RH with a significantly negative value decreases with increasing pressure until it reaches zero at a critical pressure (Pc ~ 10 GPa). Meanwhile, the corresponding Tc exhibits a slight variation within this pressure range. As pressure is further increased beyond Pc, RH changes its sign from negative to positive and then shows a slight increase, while Tc displays a continuous decrease. Our XRD measurements at 40 K demonstrate that no crystal structure phase transition occurs across the Pc. These results reveal that applying pressure to PLCCO can induce a Lifshitz transition at Pc, manifesting the reconstruction of the Fermi surface (FS), which turns the superconductivity toward fading out. Our calculation further reinforces the Fermi surface reconstruction from electron-dominated to hole-dominated ones at around Pc. These findings provide new evidence that highlights the strong correlation between the superconductivity and the Fermi surface topology in the electron-doped cuprates.

cond-mat.supr-con↗