arXiv subjects

Xing Huang

Publications and source records attributed to Xing Huang.

At least 37 records · Page 2Linked to original sources

arXiv2025

Interlayer coupling enhanced superconductivity near 100 K in La$_{3-x}$Nd$_x$Ni$_2$O$_7$

Systematically controlling the superconducting transition temperature ($T_\text{c}$) in the bilayer Ruddlesden-Popper nickelate La$_3$Ni$_2$O$_7$ remains a significant challenge. Here, we address this by synthesizing high-quality polycrystalline La$_{3-x}$Nd$_x$Ni$_2$O$_7$ ($0 \leq x \leq 2.4$) with record-level rare-earth substitution. Nd doping compresses the lattice, particularly along the $c$ axis, enhances the spin density wave transition temperature, and elevates the pressure required for the orthorhombic-to-tetragonal structural transition. Superconductivity is observed across all doping levels under high pressures, with the onset $T_\text{c}$ rising to $\sim$93~K for $x = 2.1$ and $2.4$ from the electronic transport measurement. Using the radio-frequency transmission technique, newly applied to nickelate superconductors, we detect signatures of superconductivity at $98 \pm 2$~K in the $x=2.4$ compound, pushing the $T_\text{c}$ frontier further. We identify a universal linear relationship where $T_\text{c}$ decreases with the $c$-axis lattice parameter at a rate of approximately $-28$~K/Å, demonstrating that enhanced interlayer magnetic exchange coupling is the dominant mechanism for superconducting pairing. Our work establishes the critical role of magnetism and provides a unified structural descriptor for elevating $T_\text{c}$ in bilayer nickelates.

cond-mat.supr-con↗

arXiv2025

Superconductivity in monolayer-trilayer phase of La$_3$Ni$_2$O$_7$ under high pressure

The discovery of 80 K superconductivity in pressurized bilayer Ruddlesden-Popper (RP) nickelate La$_3$Ni$_2$O$_7$ has established a new high-temperature superconductor family. The quest to understand the governing principles of RP nickelate superconductivity has become a central focus in condensed matter physics. Here, we report a critical advance by synthesizing and investigating a distinct structural polymorph of the same compound: the monolayer-trilayer (1313) hybrid phase of La$_3$Ni$_2$O$_7$. Under high pressure, synchrotron X-ray diffraction and Raman spectroscopy reveal a structural transition from the orthorhombic $Cmmm$ to the tetragonal $P4/mmm$ space group at 13~GPa. Above 19 GPa, the phase exhibits a clear superconducting transition, confirmed by a zero-resistance state, albeit at a significantly reduced temperature of 3.6 K. The stark contrast with the 80 K transition in the bilayer phase provides a uniquely clean experimental comparison. Our results demonstrate that the superconducting transition temperature is directly governed by the nature of the interlayer coupling, and the bilayer NiO$_6$ block as the essential structural motif for achieving high-$T_\text{c}$ superconductivity in the RP nickelates.

cond-mat.supr-con↗

arXiv2025

Exponential Ergodicity in Relative Entropy and $L^2$-Wasserstein Distance for non-equilibrium partially dissipative Kinetic SDEs

In this paper, we derive exponential ergodicity in relative entropy for general kinetic SDEs under a partially dissipative condition. It covers non-equilibrium situations where the forces are not of gradient type and the invariant measure does not have an explicit density, extending previous results set in the equilibrium case. The key argument is to establish the hypercontractivity of the associated semigroup, which follows from its hyperboundedness and its $L^2$-exponential ergodicity. Moreover, we obtain exponential ergodicity in the $L^2$-Wasserstein distance by combining Talagrand's inequality with a log-Harnack inequality. These results are further extended to the McKean-Vlasov setting and to the associated mean-field interacting particle systems, with convergence rates that are uniform in the number of particles in the latter case, under small nonlinear perturbations.

math.PR↗

arXiv2025

Log-Harnack Inequality and Bismut Formula for McKean-Vlasov SDEs with Singularities in all Variables

The log-Harnack inequality and Bismut formula are established for McKean-Vlasov SDEs with singularities in all (time, space, distribution) variables, where the drift satisfies an integrability condition in time-space, and the continuity in distribution may be weaker than Dini. The main results considerably improve the existing ones for the case where the drift is $L$-differentiable and Lipschitz continuous in distribution with respect to the 2-Wasserstein distance.

math.PR↗

arXiv2025

Ground state and magnetic transitions of the orthorhombic antiferromagnet CaCo$_2$TeO$_6$

We report the systematic synthesis, crystal structure, magnetization, and powder neutron diffraction of single crystalline and polycrystalline CaCo$_2$TeO$_6$ samples. CaCo$_2$TeO$_6$ crystallizes in an orthorhombic structure with $Pnma$ space group, featuring chains of edge-shared CoO$_6$ octahedra arranged in a honeycomb pattern. Two antiferromagnetic transitions are observed at $T$$_{N1}$ = 14.4 K and $T$$_{N2}$ = 16.2 K, corresponding to two long-range magnetic orders with propagation vectors of $\bf{k}$$_1$ = (0, 0, 0) and $\bf{k}$$_2$ = (0.125, 0, 0.25), respectively. The ground state is determined as a canted up-up-down-down zigzag spin configuration along the $c$ axis, wherein the magnetic moments of Co1 and Co2 ions are 3.4(1) and 2.1(1)$μ$$_B$, respectively. Successive spin-flop transitions appear with the increasing magnetic field applied along the easy axis ($c$ axis), accompanied by depression of the antiferromagnetic orders and enhancement of residual magnetic entropy. The field-induced spin-disordered state suggests that CaCo$_2$TeO$_6$ may be an ideal candidate for studying frustrated magnetism.

cond-mat.str-el↗

arXiv2025

Doping dependence of the magnetic ground state in the frustrated magnets Ba$_2$$M$Te$_{1-x}$W$_{x}$O$_6$ ($M$ = Mn, Co)

Theoretically, the relative change of the Heisenberg-type nearest-neighbor coupling $J_1$ and next-nearest-neighbor coupling $J_2$ in the face-centered-cubic lattice can give rise to three main antiferromagnetic orderings of type-I, type-II, and type-III. However, it is difficult to tune the $J_2/J_1$ ratio in real materials. Here, we report studies on the influence of Te$^{6+}$ and W$^{6+}$ ions replacement to the magnetic interactions and the magnetic ground states in the double-perovskite compounds Ba$_2$$M$Te$_{1-x}$W$_{x}$O$_6$ ($M$ = Mn, Co). For Ba$_2$MnTe$_{1-x}$W$_{x}$O$_6$, the W$^{6+}$ doping on Te$^{6+}$ site is successful in $0.02 \leq x \leq 0.9$ with short-range orders of the type-I ($0.02 \leq x \leq 0.08$) and type-II ($0.1 \leq x \leq 0.9$). In Ba$_2$CoTe$_{1-x}$W${_x}$O$_6$, x-ray diffraction measurements reveal two crystal structures, including the trigonal phase ($0 \leq x \leq 0.1$) and the cubic phase ($0.5 \leq x \leq 1$), between which is a miscibility gap. Two magnetic transitions are identified in the trigonal phase due to two magnetic subsystems, and the type-II magnetic order is observed in the cubic phase. Magnetic phase diagrams of Ba$_2M$Te$_{1-x}$W$_{x}$O$_6$ ($M$ = Mn, Co) are established. Our work shows that the magnetic interactions and ground states of Ba$_2$$M$Te$_{1-x}$W$_x$O$_6$ can be tuned effectively by the replacement of Te$^{6+}$ by W$^{6+}$ ions.

cond-mat.str-el↗

arXiv2025

Identification of the superconductivity in bilayer nickelate La$_3$Ni$_2$O$_7$ upon 100 GPa

Identification of superconductivity in the Ruddlesden-Popper phases of nickelates under high pressure remains challenging. Here, we report a comprehensive study of the crystal structure, resistance, and Meissner effect in single crystals of La$_3$Ni$_2$O$_7$ with hydrostatic pressures up to 104 GPa. X-ray diffraction measurements reveal a structural transition from the orthorhombic to a tetragonal phase above 40 GPa. Zero resistance of the superconductivity was achieved with a maximum onset $T_c^{onset}$ of 83 K at 18.0 GPa. Superconductivity is gradually suppressed until it disappears above 80 GPa, resulting in a right-triangle-like superconducting region. The direct-current magnetic susceptibility technique successfully detected the Meissner effect in La$_3$Ni$_2$O$_7$ under pressure; the maximum superconducting volume fraction is estimated to be 62.7% at 22.0 GPa. Thus, we demonstrate the bulk nature of superconductivity in the bilayer nickelate La$_3$Ni$_2$O$_7$ single crystals under high pressure. The results reveal intimate connections among the superconductivity, oxygen content, and structure in La$_3$Ni$_2$O$_7$.

cond-mat.supr-con↗

arXiv2025

Low volume fraction of high-Tc superconductivity in La3Ni2O7 at 80 K and ambient pressure

The discovery of superconductivity in pressurized La3Ni2O7 with a transition temperature of approximately 80 K above the boiling point of liquid nitrogen has sparked significant attention. It is essential to search for high-temperature superconductivity in bulk samples and at ambient pressure in nickelates. In this study, we report influential factors that affect the appearance of superconductivity in La3Ni2O7 at ambient pressure. From direct-current magnetic measurements, we observe a clear diamagnetic response at 80 K in post-annealed single crystals of La3Ni2O7 in oxygen. The superconducting volume fraction is estimated to be within 0.2%, resulting in a decrease in resistivity. This work presents a practical approach for further investigating high-temperature superconductivity in nickelates at ambient pressure.

cond-mat.supr-con↗

arXiv2025

Exponential Ergodicity in $\W_1$ for SDEs with Distribution Dependent Noise and Partially Dissipative Drifts

Being concerned with ergodicity of McKean--Vlasov SDEs, we establish a general result on exponential ergodicity in the $L^1$-Wasserstein distance. The result is successfully applied to non-degenerate and multiplicative Brownian motion cases, degenerate second order systems, and even the additive $α$-stable noise, where the coefficients before the noise are allowed to be distribution dependent and the drifts are only assumed to be partially dissipative. Our results considerably improve existing ones whose coefficients before the noise are distribution-free.

math.PR↗

arXiv2025

Beyond the band edge: Unveiling high-mobility hot carriers in a two-dimensional conjugated coordination polymer

Hot carriers, inheriting excess kinetic energy from high-energy photons, underpin numerous optoelectronic applications involving non-equilibrium transport processes. Current research on hot carriers has predominantly focused on inorganic materials, with little attention paid to organic-based systems due to their ultrafast energy relaxation and inefficient charge transport. Here, we overturn this paradigm by demonstrating highly mobile hot carriers in solution-processable, highly crystalline two-dimensional conjugated coordination polymer (2D c-CP) Cu3BHT (BHT = benzenehexathiol) films. Leveraging a suite of ultrafast spectroscopic and imaging techniques, we unravel the microscopic charge transport landscape in Cu3BHT films following non-equilibrium photoexcitation across temporal, spatial, and frequency domains, revealing two distinct high-mobility transport regimes. In the non-equilibrium transport regime, hot carriers achieve ultrahigh mobility of ~2,000 cm2 V-1 s-1, traversing grain boundaries up to 300 nm within a picosecond. In the quasi-equilibrium transport regime, free carriers exhibit Drude-type band-like transport with a remarkable mobility of ~400 cm2 V-1 s-1 and an intrinsic diffusion length exceeding 1 micrometer. These findings establish 2D c-CPs as versatile platforms for exploring high-mobility non-equilibrium transport, unlocking new opportunities for organic-based hot carrier applications.

cond-mat.mtrl-sci↗

arXiv2024

Complex-valued 3D atomic spectroscopy with Gaussian-assisted inline holography

When a laser-cooled atomic sample is optically excited, the envelope of coherent forward scattering can often be decomposed into a few complex Gaussian profiles. The convenience of Gaussian propagation helps addressing key challenges in digital holography. In this work, we develop a Gaussian-decomposition-assisted approach to inline holography, for single-shot, simultaneous measurements of absorption and phase-shift profiles of small atomic samples sparsely distributed in 3D. The samples' axial positions are resolved with micrometer resolution, and their spectroscopy are extracted from complex-valued images recorded at various probe frequencies. The phase-angle readout is not only robust against transition saturation, but also insensitive to atom-number and optical-pumping-induced interaction-strength fluctuations. Benefiting from such features, we achieve hundred-kHz-level single-shot resolution to the transition frequency of a $^{87}$Rb D2 line, with merely hundreds of atoms. We further demonstrate single-shot 3D field sensing by measuring local light shifts to the atomic array with micrometer spatial resolution.

physics.atom-ph↗

arXiv2024

Coupling Methods and Applications on Path Dependent McKean-Vlasov SDEs

By using coupling by change of conditional probability measure, the log-Harnack inequality for path dependent McKean-Vlasov SDEs with distribution dependent diffusion coefficients is established, which together with the exponential contractivity in $L^2$-Wasserstein distance yields the exponential contractivity in entropy-cost under the uniformly dissipative condition. When the coefficients are only partially dissipative, the exponential contractivity in $L^1$-Wasserstein distance is also derived in the aid of asymptotic reflection coupling, which is new even in the distribution independent case. In addition, the uniform in time propagation of chaos in $L^1$- Wasserstein distance is also obtained for path dependent mean field interacting particle system.

math.PR↗

arXiv2024

Signature of Superconductivity in Pressurized Trilayer-nickelate Pr$_4$Ni$_3$O$_{10-δ}$

The discovery of high-temperature superconductivity in La$_3$Ni$_2$O$_7$ and La$_4$Ni$_3$O$_{10}$ under pressure has drawn extensive attention. Herein, we report systematic investigations on the evolutions of structure, magnetism, and electrical resistance of Pr$_4$Ni$_3$O$_{10-δ}$ polycrystalline samples under various pressures. Pr$_4$Ni$_3$O$_{10-δ}$ exhibits density wave transitions on Ni and Pr sublattices at about 158 K and 4.3 K, respectively, and the density wave can be progressively suppressed by pressure. A structural transformation from the monoclinic $P2_1/a$ space group to the tetragonal $I4/mmm$ occurs at around 20 GPa. An apparent drop in resistance with evident magnetic field dependence is observed as pressure above 20 GPa, indicating the emergence of superconductivity in Pr$_4$Ni$_3$O$_{10-δ}$ polycrystalline samples. The discovery of the signature of superconductivity in Pr$_4$Ni$_3$O$_{10-δ}$ broadens the family of nickelate superconductors and provides a new platform for investigating the mechanisms of superconductivity in the Ruddlesden-Popper phases of nickelates.

cond-mat.supr-con↗

arXiv2024

ETROC1: The First Full Chain Precision Timing Prototype ASIC for CMS MTD Endcap Timing Layer Upgrade

We present the design and characterization of the first full chain precision timing prototype ASIC, named ETL Readout Chip version 1 (ETROC1) for the CMS MTD endcap timing layer (ETL) upgrade. The ETL utilizes Low Gain Avalanche Diode (LGAD) sensors to detect charged particles, with the goal to achieve a time resolution of 40 - 50 ps per hit, and 30 - 40 ps per track with hits from two detector layers. The ETROC1 is composed of a 5 x 5 pixel array and peripheral circuits. The pixel array includes a 4 x 4 active pixel array with an H-tree shaped network delivering clock and charge injection signals. Each active pixel is composed of various components, including a bump pad, a charge injection circuit, a pre-amplifier, a discriminator, a digital-to-analog converter, and a time-to-digital converter. These components play essential roles as the front-end link in processing LGAD signals and measuring timing-related information. The peripheral circuits provide clock signals and readout functionalities. The size of the ETROC1 chip is 7 mm x 9 mm. ETROC1 has been fabricated in a 65 nm CMOS process, and extensively tested under stimuli of charge injection, infrared laser, and proton beam. The time resolution of bump-bonded ETROC1 + LGAD chipsets reaches 42 - 46 ps per hit in the beam test.

physics.ins-det↗

arXiv2024

Quantitative Propagation of Chaos in $L^η(η\in(0,1])$-Wasserstein distance for Mean Field Interacting Particle System

In this paper, quantitative propagation of chaos in $L^η$($η\in(0,1]$)-Wasserstein distance for mean field interacting particle system is derived, where the diffusion coefficient is allowed to be interacting and the initial distribution of interacting particle system converges to that of the limit equation in $L^1$-Wasserstein distance. The non-degenerate and second order system are investigated respectively and the main tool relies on the gradient estimate of the decoupled SDEs.

math.PR↗

arXiv2024

Long Time $\W_0$-$\widetilde{\W}_1$ type Propagation of Chaos for Mean Field Interacting Particle System

In this paper, a general result on the long time $\W_0$-$\widetilde{\W}_1$ type propagation of chaos, propagation of chaos with regularization effect, for mean field interacting particle system driven by Lévy noise is derived, where $\W_0$ is one half of the total variation distance while $\widetilde{\W}_1$ is the $L^1$-Wasserstein distance. By using the method of coupling, the general result is applied to mean field interacting particle system driven by multiplicative Brownian motion and additive $α(α>1)$-stable noise respectively, where the non-interacting drift is assumed to be dissipative in long distance and the initial distribution of interacting particle system converges to that of the limit equation in $\widetilde{\W}_1$.

math.PR↗

arXiv2024

Modular Average and Weyl Anomaly in Two-Dimensional Schwarzian Theory

The gauge formulation of Einstein gravity in AdS$_3$ background leads to a boundary theory that breaks modular symmetry and loses the covariant form. We examine the Weyl anomaly for the cylinder and torus manifolds. The divergent term is the same as the Liouville theory when transforming from the cylinder to the sphere. The general Weyl transformation on the torus also reproduces the Liouville theory. The Weyl transformation introduces an additional boundary term for reproducing the Liouville theory, which allows the use of CFT techniques to analyze the theory. The torus partition function in this boundary theory is one-loop exact, and an analytical solution to disjoint two-interval Rényi-2 mutual information can be obtained. We also discuss a first-order phase transition for the separation length of two intervals, which occurs at the classical level but is smoothed out by non-perturbative effects captured by averaging over a modular group in the boundary theory.

hep-th↗

arXiv2024

On-liquid-gallium surface synthesis of ultra-smooth conductive metal-organic framework thin films

Conductive metal-organic frameworks (MOFs) are emerging electroactive materials for (opto-)electronics. However, it remains a great challenge to achieve reliable MOF-based devices via the existing synthesis methods that are compatible with the complementary metal-oxide-semiconductor technology, as the surface roughness of thus-far synthetic MOF films or pellets is rather high for efficient electrode contact. Here, we develop an on-liquid-gallium surface synthesis (OLGSS) strategy under chemical vapor deposition (CVD) conditions for the controlled growth of two-dimensional conjugated MOF (2D c-MOF) thin films with ten-fold improvement of surface flatness (surface roughness can reach as low as ~2 Å) compared with MOF films grown by the traditional methods. Supported by theoretical modeling, we unveil a layer-by-layer CVD growth mode for constructing flattening surfaces, that is triggered by the high adhesion energy between gallium (Ga) and planar aromatic ligands. We further demonstrate the generality of the as-proposed OLGSS strategy by reproducing such a flat surface over nine different 2D c-MOF films with variable thicknesses (~2 to 208 nm) and large lateral sizes (over 1 cm2). The resultant ultra-smooth 2D c-MOF films enable the formation of high-quality electrical contacts with gold (Au) electrodes, leading to a reduction of contact resistance by over ten orders of magnitude compared to the traditional uneven MOF films. Furthermore, due to the efficient interfacial interaction benifited from the high-quality contacts, the prepared van der Waals heterostructure (vdWH) of OLGSS c-MOF and MoS2 exhibits intriguing photoluminescence (PL) enhancement, PL peak shift and large work function modulation. The establishment of the reliable OLGSS method provides the chances to push the development of MOF electronics and the construction of multicomponent MOF-based heterostructure materials.

physics.app-ph↗