arXiv subjects

Shu-Xiang Qiao

Publications and source records attributed to Shu-Xiang Qiao.

5 recordsLinked to original sources

arXiv2026

Prediction of 1:1 kagome metals with superconductivity and band topology

Kagome superconductors featuring topologically nontrivial band structures have attracted extensive research interest. FeSn and CoSn is a new kind of kagome material with intrinsic magnetism, which suppresses the emergence of superconductivity. Here, we theoretically predict a new kind of 1:1 kagome MSn (M=transition metal), which exhibit intrinsic superconductivity and nontrivial band topology by first-principles calculations. Among twenty-seven candidates, MSn (M= Mo, Hf, Nb, Ta, W, Ti) are theoretically identified as both dynamically and thermodynamical stable. And, five non-magnetic MSn (M= Mo, Hf, Nb, Ta, W) exhibit phonon-mediated superconductivity. Especially, the d orbitals bands display Dirac points and van Hove singularities near the Fermi level, which contribute to the emergence of topology and the electron-phonon coupling (EPC). More interestingly, MoSn, HfSn and NbSn show nontrivial topological band structure at the Fermi level. Thus, the predicted MSn establish a platform integrating superconductivity and topological order.

cond-mat.supr-con↗

arXiv2026

Intertwined charge density wave, tunable anti-dome superconductivity, and topological states in kagome metal VSn

These years, kagome materials with 1:1 stoichiometry have garnered increasing attention, among which FeSn, CoSn, and FeGe have been the focus of current studies. However, all of them are antiferromagnetic, thereby hindering the observation of superconductivity and other novel physical properties. Here, we predict a novel 1:1 kagome metal VSn, which is an intrinsic charge density wave (CDW) material. Interestingly, with increasing pressure or doping concentration, the CDW order is progressively suppressed, followed by the emergence of superconductivity characterized by a non-monotonic transition temperature that exhibits a rare anti-dome-shaped dependence. Above a critical threshold, a reentrance of the CDW phase occurs. The anti-dome superconductivity originates from the first hardening and then softening of phonon modes, together with band reconstruction. Crucially, VSn retains nontrivial topological properties across the entire superconducting regime, a feature of paramount importance for realizing robust topological superconductivity. These intertwined CDW, superconductivity, and topological phenomena elucidate the correlations among multiple quantum states in VSn. Therefore, this research paves the way for for designing 1:1 kagome superconducting topological metals and establishes a platform for exploring the interplay of multiple phases in kagome systems.

cond-mat.mtrl-sci↗

arXiv2026

Two-gap to Single-gap Transition and Two-dome-like Superconductivity in Alkali-Metal Intercalated Bilayer PdTe2

PdTe2 has been synthesized with controllable thickness down to the monolayer limit. Based on first-principles calculations within the fully anisotropic Migdal-Eliashberg framework, this work reveals that alkali-metal intercalation markedly enhances the weak superconductivity of bilayer PdTe2, boosting the transition temperature from 1.4 K to 5.0 -13.5 K and yielding a two-dome-like evolution of Tc. Rubidium intercalation induces the highest Tc of 13.5 K, which can be further increased to 14.5 K under biaxial tensile strain. The strain-dependent evolution of Tc also exhibits a two-dome-like behavior, reflecting the interplay between strain-induced band structure modifications and electron-phonon coupling (EPC). Moreover, a systematic correlation is identified between interlayer interaction and superconducting gap. Lithium intercalation induces a distinct two-gap state, whereas intercalants with larger atomic radii (Na, K, Rb, and Cs) drive the system into a single-gap character. The two-gap to single-gap transition originates from the modulation of interlayer coupling through intercalation-induced interlayer expansion. In addition, pristine and Li/Na-intercalated bilayers exhibit nontrivial band topology, suggesting that layered PdTe2 provides a promising platform for realizing the coexistence of superconductivity and nontrivial topology. These results provide detailed anisotropic insights into EPC and offer viable pathways for enhancing Tc and achieving diverse properties in layered PdTe2 systems.

cond-mat.supr-con↗

arXiv2025

Two-dimensional transition metal selenides family M2Se: A platform for superconductivity, band topology, and charge density waves

MXenes and MBenes, which are two-dimensional (2D) transition metal carbides/nitrides and borides, have been extensively studied for their impressive properties. Recently, we reported a family of transition metal sulfides MSene (M2S) with rich properties [Phys. Rev. B 111, L041404 (2025)], it is worth studying whether selenides with similar structure also have rich properties. In this work, through high-throughput screening, we present a novel family of 2D transition metal selenides, M2Se. In this family, there are fifty-eight candidate materials, of which ten are stable and metallic. Notably, eight exhibit superconductivity, among which four are superconducting topological metals. Besides, eight show charge density wave (CDW) behavior, among which five also exhibit antiferromagnetism. It is revealed that CDW originates from electron-phonon coupling rather than Fermi surface nesting. Moreover, strain can be applied to regulate the competition between CDW and superconductivity. Our findings reveal the rich properties of superconductivity, band topology, CDW, and magnetism in M2Se, providing a new platform for the controllable integration of multifunctional quantum states.

cond-mat.mtrl-sci↗

arXiv2024

MSene: A new large family of two-dimensional transition metal sulfide with MXene structure

In this work, we theoretically report a new large family of two-dimensional (2D) transition metal sulfides $M$$_{2}$S with MXene structure in 2H and 1T phases, which we name as MSene. Twenty-four out of fifty-eight MSenes are proved to be stable. Notably, this family includes twelve superconducting (SC) materials, seven SC topological metals (SCTMs), four charge density wave (CDW) materials, and five magnetic materials including one ferromagnetic (FM) and four antiferromagnetic (AFM) materials. For example, 2H-Mo$_{2}$S is a SCTM which exhibits SC critical temperature ($T_{c}$) of 10.2 K and nontrivial topological properties; 1T-Hf$_{2}$S is a CDW material with the CDW originating from electron-phonon coupling. The CDW can be suppressed by compressive strain, leading to the emergence of superconductivity; 2H-Cr$_{2}$S and 1T-Mn$_{2}$S show FM and AFM properties, respectively. Thus, the new large family we predicted shows rich physical properties and significantly expands the repertoire of 2D materials. It serves as a novel platform for investigating the competition or coexistence of multiple orders such as SC, CDW, FM, AFM and topological orders in 2D materials.

cond-mat.mtrl-sci↗