Yanpeng Qi

Recent studies of sulfides have highlighted their potential for exploring unique superconductors under pressure. Here we combine crystal structure predictions with ab initio calculations on the crystal structures, electronic structures and superconducting properties of the In–S system within 80 GPa. We predicted six unique In–S sulfides within five stoichiometries. Among them, In ₂ S- C 2/ m, InS- Fm -3 m and InS- Pmmn are thermodynamically stable within certain pressure ranges, whereas In ₃ S- P 4/ nmm , InS ₅ - P 2 ₁ / m and InS ₆ - P -6 are meta-stable. With the increase of S content, we can observe varied contributions to electronic structures from In and S atoms, and the S-rich phases correspond to better superconductivity in our predicted In–S sulfides. In particular, the S-rich sulfides of InS ₅ - P 2 ₁ / m and InS ₆ - P -6 stand out with the estimated T _c of about 11 K at 40 GPa and 13 K at 20 GPa, respectively. By analyzing the correlation between bond strength and T _c values of other six binary sulfide systems, we summarized preliminary strategies for designing superconducting sulfides. Our work is helpful for further understanding the phase diagram of In–S system under high pressure, and could provide theoretical support for studying unique superconducting sulfides in experiments.

Electrides have been largely restricted to electron-rich compositions, leaving the applications of electron–neutral electrides scarcely explored and poorly understood. Here we report the discovery of an electron–neutral ternary electride, LiAlGe, which undergoes an unusual pressure-driven evolution: a semiconducting, nonelectride F4̅3m-LiAlGe phase at ambient conditions transforms into metallic electride phases, F4̅3m- (6.4–13.7 GPa) and Cmmm-LiAlGe phase (13.7–40.0 GPa). First-principles calculations further predict superconductivity in both high-pressure phases. To extend this concept, we combined high-throughput computation with machine learning (ML) to identify ten additional electron–neutral electrides adopting the LiAlGe-type topology. ML analysis reveals that the cooperative interplay between distinct cation species and their atomic radii is a key descriptor governing electride formation in ternary neutral systems. We synthesized LiAlGe and experimentally verified its high-pressure behavior. Synchrotron X-ray measurements confirmed the predicted F4̅3m to Cmmm transition at 14.3 GPa, in excellent agreement with the calculated 13.7 GPa. Importantly, both high-pressure phases were found to be superconducting under appropriate pressures, validating the theoretical predictions and establishing electron–neutral electrides as a previously overlooked class of superconducting materials.

Trilayer nickelates provide a tunable platform for investigating the interplay between structural geometry, electron correlation, and unconventional superconductivity. By directly comparing Pr${}_{4}$Ni${}_{3}$O${}_{10}$ and La${}_{4}$Ni${}_{3}$O${}_{10}$, this work uncovers an orbital differentiation enhanced by structural modification in Pr${}_{4}$Ni${}_{3}$O${}_{10}$, where orbitals become selectively incoherent and significantly renormalized, while orbitals remain coherent. This dichotomy leads to a marked suppression of interorbital hybridization in Pr${}_{4}$Ni${}_{3}$O${}_{10}$. This work suggests that the interlayer bonding angle serves as an active tuning parameter for the electronic properties, bridging multiorbital correlated physics and superconductivity in nickelates.

High‐temperature superconducting coated conductors are pivotal for nuclear fusion and other transformative electrical applications. However, the current‐carrying capacity of these conductors remains insufficient to realize such large‐scale applications, as it is fundamentally constrained by the “thickness effect”, an intrinsic degradation of critical current density with increasing superconducting layer thickness. Here, we report a dual‐modulation strategy that overcomes this long‐standing hurdle in pulsed‐laser‐deposited (PLD) REBa ₂ Cu ₃ O _x (REBCO, RE = rare earth) superconductors. By coupling dynamic thermal control with rare‐earth composition engineering, we effectively balance deposition flux and surface diffusion to maintain structural continuity, and suppress a ‐axis grain formation to obtain dense mixed‐dimensional artificial pinning centers. Our approach enables the growth of high‐quality REBCO layers up to 6 µm thick on technical substrates without a discernible “thickness effect”. The 6 µm‐thick coated conductors deliver unprecedented critical current of 2500 A/cm at 20 K and 10 T and 1446 A/cm at 50 K and 5 T, representing the highest values reported for all PLD‐grown REBCO conductors to date. Our results demonstrate significant performance enhancements by eliminating the “thickness effect” in REBCO films, providing a scalable route for high‐field and fusion for producing high‐temperature superconducting coated conductors that are favorable for large‐scale applications.

We investigate flux dynamics in the high-entropy alloy superconductor (TaNb)0.7(HfZrTi)0.5 after annealing (as-cast, 500, 550, and 1000 °C) using a sensitive ac composite magnetoelectric method that measures the complex ac magnetostrictive coefficient (dλ/dH)ac. The resulting vortex phase diagrams show that intermediate annealing (about 500–550 °C) induces nanoscale clustering, enhances pinning, and produces a pronounced fishtail effect with successive elastic- and plastic vortex-glass regimes. Flux-jump instabilities are observed at an annealing temperature of 550 °C and persist at 1000 °C, indicating strong pinning and thermomagnetic instability in the low-temperature, low-field regime. Remarkably, the 1000 °C sample exhibits a two-step superconducting response—a double plateau or drop in dλ′/dH and two dissipation peaks in dλ″/dH—demonstrating the coexistence of two superconducting phases with distinct irreversibility and critical-field value. We further show that the resolvability of the two-step (dλ/dH)ac signature is governed by the topological connectivity of the phase-separated microstructure, which controls magnetic shielding between the TaNb-rich network and the (TaNb)0.7(HfZrTi)0.5 parent phase. These results establish a direct microstructure–vortex-state correlation and provide a route to tailoring flux pinning in chemically complex superconductors via thermal processing.

The superconducting diode effect (SDE) is a fascinating nonreciprocal phenomenon where the critical current is different for opposite current directions. It is widely believed that realizing SDE requires breaking both inversion symmetry and time-reversal symmetry (TRS), which are usually achieved via heterostructure engineering and applying external magnetic fields. Here, we report a pressure-induced magnetic-field-free SDE in NbSe_{2} flakes without any heterostructures. We show that pressure alone breaks the inversion symmetry, as confirmed by the second harmonic generation. Crucially, upon applying an out-of-plane magnetic field (B), the SDE exhibits even-in-B behavior, implying the absence of explicit TRS breaking. This finding challenges the prevailing theoretical paradigm and demonstrates that a magnetic-field-free SDE can emerge without explicitly breaking TRS. Thereby, our Letter establishes pressure engineering as a powerful tool for inducing nonreciprocal superconductivity and designing versatile, magnetic-field-free superconducting devices.

The intrinsic electronic structures of narrow bandgap thermoelectric (TE) materials serve as a platform for the investigation of coupling effects of quasi-particles under high pressure, enabling the exploration of emerging electronic and phonon transport, superconductivity, and topological transitions. Here, we report the discovery of pressure-induced superconductivity in the TE semiconductor Mg₃Sb₂. Upon increased pressure, metallization occurs at ∼8.7 GPa, followed by a superconducting transition concomitant with a carrier-type crossover from p- to n-type. This phenomenon arises from a pressure-induced structural phase transition from the semiconducting P3̅m1 to the metallic C2/m-I phase. The superconducting critical temperature (T_c) exhibits a dome-shaped pressure dependence, peaking at 3.3 K at 12.6 GPa. Combined theoretical calculations, high-pressure Raman spectroscopy, and X-ray diffraction (XRD) measurements reveal an additional structural transition above ∼20 GPa, yielding a distinct C2/m-II phase. Our findings establish the high-pressure phase diagram of Mg₃Sb₂, elucidate its pressure-dependent electronic properties, and provide valuable insights for future investigations of TE materials under high pressure.