Publications by authors named "Zhu An Xu"
Unraveling the role of Ta in the phase transition of Pb(TaSe) using temperature-dependent Raman spectroscopy.
J Colloid Interface Sci
January 2025
Phase engineering strategies in two-dimensional transition metal dichalcogenides (2D-TMDs) have garnered significant attention due to their potential applications in electronics, optoelectronics, and energy storage. Various methods, including direct synthesis, pressure control, and chemical doping, have been employed to manipulate structural transitions in 2D-TMDs. Metal intercalation emerges as an effective technique to modulate phase transition dynamics by inserting external atoms or ions between the layers of 2D-TMDs, altering their electronic structure and physical properties.
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- Van der Waals (vdW) crystals with strong spin-orbit coupling are key for discovering unique 2D superconductors, where new pairing states arise from the combination of various factors like SOC and crystal structure.
- The study highlights a mirror-symmetry protected Ising pairing state in a heterostructure of SnSe and TaSe, where the arrangement of the lattice helps minimize interference from certain pairing mechanisms.
- The findings indicate that these vdW heterostructures can enhance the critical temperature under specific magnetic fields, which does not occur in other multilayer configurations due to a loss of mirror symmetry.
Article Synopsis
- Edge states in topological systems are important due to their stability and unique properties, leading to the development of a superconducting-proximitized edge interferometer on the topological insulator TaPdTe.
- This interferometer realizes the Josephson diode effect (JDE), achieving high efficiency (up to 73%) and ultra-low power consumption while operating under small magnetic fields.
- Key features of the JDE include the presence of a second-order harmonic in the current-phase relation and antisymmetric transport, indicating the device's effectiveness for future advancements in superconducting quantum technologies.
Article Synopsis
- The text discusses the theoretical and experimental challenges of achieving superconductivity in kagome materials, particularly highlighting nonmagnetic vanadium-based variants that do not support the expected exotic superconductivity.
- A new chromium-based kagome metal, CsCrSb, is introduced, characterized by strong electron correlations, frustrated magnetism, and flat bands near the Fermi level.
- This material undergoes a phase transition at 55 K, with density-wave orders evolving under pressure, leading to the emergence of superconductivity between 3.65-8.0 GPa, peaking at 6.4 K when these orders are suppressed, suggesting connections to unconventional superconductivity.
Article Synopsis
- The study investigates how magnetic moments in thin CrOCl, a frustrated antiferromagnet, are stabilized through coupling with different degrees of freedom, particularly lattice distortions affecting magnetic orientation.
- It reveals that the transitions between antiferromagnetic and ferrimagnetic states in CrOCl occur through a novel mechanism involving collective flipping of magnetic moments, rather than the previously understood spin-flop process.
- Additionally, the changes in electronic properties during these transitions offer potential for innovative applications in spintronics and exploring unusual physical phenomena in two-dimensional materials.
Article Synopsis
- * The superconductivity is particularly sensitive to the surface orientation of KTaO, indicating important differences from earlier systems like LaAlO/SrTiO.
- * Using ionic liquid (IL) gating, researchers achieved superconductivity on KTaO surfaces, suggesting that electron doping at the surfaces is key, and this method opens up new options for exploring the fundamental properties of superconductivity in KTaO.
Article Synopsis
- Recent advancements in magnetic, ferroelectric, and multiferroic tunnel junctions (MTJs, FTJs, AFTJs, MFTJs) are paving the way for advanced nanoscale memory devices, although traditional structures have limitations like high resistance-area (RA) product and low resistance differences.
- The discovery of two-dimensional (2D) van der Waals ferroelectric and magnetic materials has led to the proposal of a new type of tunnel junction called the antiferroelectric magnetic tunnel junction (AFMTJ), which combines features of MTJs and AFTJs.
- Through first-principles calculations, the study shows that AFMTJs, made with monolayer CuInPS (CIPS)
Article Synopsis
- - Investigating how intercalation and stacking-order modulation affect the properties of transition metal dichalcogenides (TMDCs), researchers report the growth of a new material, Pb(Ta Se ), the first example of a 124-phase TMDC.
- - Pb(Ta Se ) undergoes unique structural phase transitions at around 230 K, shifting through various stacking configurations and symmetries, which leads to significant changes in the material's lattice structure and superconducting properties.
- - The research utilizes first-principle calculations and symmetry analysis to explore the underlying physics of these transitions, revealing potential for novel metal-intercalated TMDC phases and implications for future stacking-order engineering.
Article Synopsis
- - This study focuses on the transport properties of Ba(FeCo)As single crystals, identifying key indicators of vortex unbinding related to the Berezinskii-Kosterlitz-Thouless (BKT) transition.
- - Both traditional methods and a dynamic scaling analysis reveal a Nelson-Kosterlitz jump, indicating significant changes in the behavior of the material during the transition.
- - A unique non-Hall transverse signal is detected at the superconducting transition, which the researchers attribute to the guided movement of unbound vortices within the material.
Article Synopsis
- * In this gapless state, zero-energy quasiparticles appear on part of the Fermi surface, while other parts remain gapped.
- * Using quasiparticle interference techniques, the study examines the Fermi surface of bismuth telluride thin films affected by the superconductor niobium diselenide, revealing unique interference patterns that signify a gapless superconducting state.
Article Synopsis
- This study explores how spin-orbit coupling (SOC) and the Stark effect interact in few-layer black arsenic, a non-centrosymmetric two-dimensional electronic material, leading to unique quantum phenomena.
- The interplay results in the formation of asymentrical particle-hole states and tunable Rashba valleys, which are influenced by an applied electric field that breaks symmetry in the material's structure.
- The findings reveal unconventional transitions in quantum Hall states and changes in band topology, demonstrating potential applications for controlling electronic properties in two-dimensional systems using electrostatic gating.
Coexistence of Ferroelectricity and Ferromagnetism in One-Dimensional SbN and BiN Nanowires.
ACS Appl Mater Interfaces
March 2021
Article Synopsis
- Ferroelectricity, important for electronics, is usually found in three- and two-dimensional materials, but is rare in one-dimensional materials.
- Researchers have discovered that one-dimensional SbN and BiN nanowires exhibit ferroelectricity with polarization strengths significantly higher than previously seen in one-dimensional structures.
- Additionally, these nanowires can show spontaneous spin polarization with moderate hole doping, marking the first instance of both ferroelectricity and ferromagnetism occurring together in a one-dimensional system, which could lead to new electronic and spintronic applications.
Anisotropic gapping of topological Weyl rings in the charge-density-wave superconductor InTaSe.
Sci Bull (Beijing)
February 2021
Article Synopsis
- * The researchers observed two types of charge density wave (CDW) phases within the material at different temperatures, which interact with its topological features, specifically nodal rings (Weyl rings).
- * Superconductivity was detected at a low temperature (0.91 K) in this material, suggesting the potential for unconventional superconducting behavior and a rich array of physical phenomena for further exploration.
Article Synopsis
- The study explores how the magnetoelectric effect can be used to control magnetic properties for future data storage devices, allowing for the switching of magnetic states through electric fields.
- First-principles calculations show that changing the electric polarization of a 2D ferroelectric substrate (α-InSe) affects the magnetic properties of metal-phthalocyanine molecules (MPc), specifically OsPc.
- The findings indicate that by modifying the system with functionalized atoms, the magnetic moments and magnetic anisotropy energies can be significantly enhanced, making this technique potentially useful for nanoscale electronics and spintronics at room temperature.
Article Synopsis
- Monolayer dialkali-metal monoxides in a 2H-MoS lattice exhibit unique symmetry-protected topological phases that can be fine-tuned through strain engineering.
- In equilibrium, monolayer sodium oxide (NaO) behaves as a 2D double Weyl semimetal, while monolayer potassium oxide (KO) acts as a 2D pseudospin-1 metal, both displaying interesting optical and tunneling properties.
- By applying biaxial or uniaxial strain, these materials can undergo quantum phase transitions, making them a promising platform for studying new physical phenomena related to 2D emergent fermions.
Article Synopsis
- The study investigates quantum phase transitions in CeNi(AsP) nickel pnictides, focusing on their heavy fermion behavior under varying phosphorus content.
- It reveals that increasing phosphorus concentration leads to a suppression of antiferromagnetic order and a transition to non-Fermi liquid behavior, particularly noticeable at x ~ 0.55.
- The research highlights that this non-Fermi liquid behavior persists over a range of doping concentrations (x < 0.9) and contrasts with the behavior observed in the compound at zero doping under pressure, indicating a unique phase in heavy fermion metals.
Magnetic and transport properties of low-carrier-density Kondo semimetal CeSbTe.
J Phys Condens Matter
September 2019
Article Synopsis
- * Physical properties were studied through various measurements, identifying an antiferromagnetic transition linked to Ce ions and a field-induced metamagnetic transition.
- * CeSbTe is characterized as a moderately correlated antiferromagnetic Kondo lattice compound with low carrier density, suggesting its unique behavior as a Kondo semimetal.
Dialkali-Metal Monochalcogenide Semiconductors with High Mobility and Tunable Magnetism.
J Phys Chem Lett
December 2018
Article Synopsis
- The discovery of new two-dimensional (2D) materials like dialkali-metal monochalcogenides (DMMCs) opens up opportunities for significant advances in both science and technology.
- DMMCs feature a unique atomic structure that provides excellent stability, a wide energy gap, and high electron mobility, making them very promising for various applications.
- Notably, these materials can exhibit ferromagnetism upon certain doping conditions, suggesting potential for innovative developments in fields like spintronics and optoelectronics.
Article Synopsis
- Large-sized single crystals of the misfit layered compound (SnSe)(NbSe) were successfully grown, revealing superconductivity at a critical temperature (T) of 3.4 K for the first time.
- Techniques like powder x-ray diffraction and high-resolution transmission electron microscopy confirm the unique misfit structure between the SnSe and NbSe layers.
- Measurements indicate that this compound exhibits a relatively high Sommerfeld coefficient (γ) of 16.73 mJ mol K, a specific heat jump near 0.98, an estimated electron-phonon coupling constant of 0.80, and a multi-band superconducting nature suggested by the critical magnetic field value of around 7.82 T.
Article Synopsis
- Transition-metal chalcogenides exhibit various phases such as CDW, superconductors, and topological insulators, sparking significant research interest in their properties.
- The study reports the discovery of pressure-induced superconductivity in the quasi-one-dimensional compound NbTe, originally a CDW material at normal pressure.
- At high pressures (over 12.4 GPa), superconductivity is observed with a transition temperature of 2.2 K, alongside a notable magnetoresistance of 102% at low temperatures, highlighting NbTe's unique characteristics compared to typical CDW materials.
Article Synopsis
- A new compound called KMnBi has been discovered, featuring quasi-one-dimensional nanowires made of manganese (Mn) and bismuth (Bi) atoms arranged in a unique structure.
- The Mn atoms form nanorods centered in Bi nanotubes, stabilized by Mn-Mn bonding and linked by weak Bi-Bi bonds while being balanced by potassium (K) ions.
- Magnetic studies show the compound exhibits antiferromagnetic behavior at around 75 K and a shift in resistivity from semiconducting to metallic as temperature decreases, indicating changes in how electrons move between columns.
Article Synopsis
- TaSe exhibits various polytypes with notable physical properties like superconductivity and charge density waves (CDW), but the 4Ha polytype had not been studied until now.
- Researchers successfully grew a 4Ha-TaSe single crystal that shows superconductivity at an onset temperature of [Formula: see text] K, marking the first observation of this phenomenon in this specific polytype.
- The study also finds a slight suppression of the CDW transition at around 106 K, a high value of about 4.48 when a magnetic field is applied, and special stacking faults that contribute to the material's anisotropy, suggesting a unique interplay between its stacking mode and superconductivity.
Article Synopsis
- - SnSe shows great potential as a thermoelectric material but lacks a full understanding of its electronic structure and self-hole-doping mechanism.
- - Researchers used angle-resolved photoemission spectroscopy to reveal a unique valence band shape in SnSe and found that p-type doping is influenced by local phase segregation and charge transfer.
- - The study observed quantum transport phenomena and a complex 3D Fermi surface in p-SnSe, suggesting that manipulating defects could enhance the material's thermoelectric performance.
Article Synopsis
- Ultrathin bismuth films are identified as potential two-dimensional topological insulators, but their properties are influenced by factors such as film thickness and substrate interactions.
- Research utilizing advanced techniques like angle-resolved photoemission spectroscopy shows that Bi(111) films on a NbSe substrate exhibit quasi-freestanding band structures and one-dimensional edge states even at just three bilayers thick.
- The coexistence of these topological edge states and superconductivity, with pairing potential diminishing as layer thickness increases, positions the system as an exciting opportunity for investigating Majorana Fermions.
Article Synopsis
- * The compound exhibits bulk superconductivity at a certain temperature, confirmed through various measurements including electrical resistivity, magnetic susceptibility, and heat capacity.
- * The study highlights an impressive initial slope of the upper critical field for the polycrystalline sample, indicating strong superconducting properties.