Ming Yang

The Hong Kong Polytechnic University | PolyU · Department of Applied Physics

Two-dimensional (2D) perovskite oxide interfaces are ideal systems to uncover diverse emergent properties, such as the arising polaronic properties from short-range charge–lattice interactions. Thus, a technique to detect this quasiparticle phenomenon at the buried interface is highly coveted. Here, we report the observation of 2D small-polarons at...

Charge density waves (CDWs), a common phenomenon of periodic lattice distortions, often suppress ferromagnetism in two-dimensional (2D) materials, hindering their magnetic applications. Here, we report a novel CDW that generates 2D ferromagnetism instead of suppressing it, through the formation of interstitial anionic electrons as the charge modula...

Oxide heterostructures have shown rich physics phenomena, particularly in the conjunction of exotic insulator–metal transition (IMT) at the interface between polar insulator LaAlO3 and non-polar insulator SrTiO3 (LaAlO3/SrTiO3). The polarization catastrophe model has suggested an electronic reconstruction, yielding to metallicity at both the interf...

Manipulating spin polarization orientation is challenging but crucial for field-free spintronic devices. Although such manipulation has been demonstrated in a limited number of antiferromagnetic metal-based systems, the inevitable shunting effects from the metallic layer can reduce the overall device efficiency. In this study, we propose an antifer...

SrTiO 3 (STO), a room-temperature paraelectric material in bulk form, has been a rich playground for emergent phenomena for decades. As an emerging material, great attention has been paid to freestanding 2D STO thin films. Recently, the room-temperature ferroelectricity has been unveiled in strained STO thin films; however, it remains an open quest...

Elemental carbon has been successfully used to tune the light emission properties of zinc oxide (ZnO) through artificially doping but the underlying mechanism remains controversial. At present, carbon-related defect complexes are the main explanation. Nevertheless, the possibility of forming semiconducting Zn-C compounds has not been discussed. In...

Switchable polarization in ferroelectric catalysts shows promise to overcome Sabatier limitation imposed on traditional catalysts. However, a comprehensive understanding of the polarization effect on the electrocatalytic performance remains elusive. In this study, using ferroelectric BaTiO3 (BTO) as a model system, we report tunable hydrogen evolut...

The Au (100) surface has been a subject of intense studies due to excellent catalytic activities and its model character for surface science. However, the spontaneous surface reconstruction buries active Au (100) plane and limits practical applications, and how to controllably eliminate the surface reconstruction over large scale remains challengin...

Exploiting inexpensive and effective nickel-based catalysts that produce hydrogen from liquid organic hydrogen carriers (LOHCs) is crucial to alleviating the global energy and environmental crisis. In this study, we report a rational strategy that can realize atomically dispersed Ni atoms anchored on vacancy-abundant boron nitride nanosheets (Ni1/h...

The conventional four-electron electrochemical process which drives water splitting requires a high overpotential and is energy inefficient. Thus, it is highly desirable to develop an alternative theoretical framework for catalyst...

Memory transistors based on two-dimensional (2D) ferroelectric semiconductors are intriguing for next-generation in-memory computing. To date, several 2D ferroelectric materials have been unveiled, among which 2D In2Se3 is the most promising, as all the paraelectric (β), ferroelectric (α) and antiferroelectric (β′) phases are found in 2D quintuple...

Ferrimagnets with magnetic compensation temperature ( T comp ) around room temperature are desirable due to their potential applications in low-energy consuming and high-frequency spintronic devices. In this study, the T comp of ferrimagnetic Mn 2.21 Ru 0.86 Ga (MRG) is tuned to near room temperature by strain. Moreover, we observed unconventional...

Two-dimensional (2D) perovskite oxide interfaces are ideal systems where diverse emergent properties can be uncovered.The formation and modification of polaronic properties due to short-range strong charge-lattice interactions of 2D interfaces remains hugely intriguing.Here, we report the direct observation of small-polarons at the LaAlO3/SrTiO3 (L...

Phase transitions in two-dimensional (2D) materials promise reversible modulation of material physical and chemical properties in a wide range of applications. 2D van der Waals layered In 2 Se 3 with bistable out-of-plane ferroelectric (FE) α phase and antiferroelectric (AFE) β′ phase is particularly attractive for its electronic applications. Howe...

Two-dimensional (2D) semiconductors could potentially replace silicon in future electronic devices. However, the low carrier mobility in 2D semiconductors at room temperature, caused by strong phonon scattering, remains a critical challenge. Here we show that lattice distortions can reduce electron–phonon scattering in 2D materials and thus improve...

The multi‐layer 2D materials have attracted increasing interest because the intriguing properties can be achieved by various strategies, such as incorporating ions into the interlayer, turning angles between two layers, and applying strain, which may lead to wide applications in catalysis, ion‐batteries, superconductors, and nanodevices. In this wo...

Multilevel resistive switching in memristive devices is vital for applications in non-volatile memory and neuromorphic computing. In this study, we report on the multilevel resistive switching characteristics in SnSe/SrTiO3(STO) heterojunction-based memory devices with silver (Ag) and copper (Cu) top electrodes. The SnSe/STO-based memory devices pr...

In this Letter, the fabrication of large-scale (50.8 mm in diameter) few-layered MoS2 with physical vapor deposition on sapphire is described. Open-aperture Z-scan technology with a home-made excitation source at 2275 nm was applied to explore its nonlinear saturable absorption properties. The as-grown few-layered MoS2 membrane possessed a modulati...

Polycyclic hydrocarbons (PHs) share the same hexagonal structure of sp2 carbons as graphene but possess an energy gap due to quantum confinement effect. PHs can be synthesized by a bottom-up strategy starting from small building blocks covalently bonded into large 2D organic sheets. Further investigation of the role of the covalent bonding/coupling...

Resistive switching devices with a high self-rectifying ratio are important for achieving the crossbar memristor array that overcomes the sneak current issue. Herein, we demonstrate a single amorphous lithium lanthanum titanium oxide (LLTO) layer based Pt/LLTO/Pt device possessing a self-rectifying ratio higher than 1 × 10⁴ that is comparable to th...

The surface‐enhanced Raman scattering (SERS) as a novel and efficient analytic technique to probe molecules has attracted tremendous attention. Semiconducting substrates have been widely investigated for their applications into SERS because of their easy integration with electronic devices. In this work, a wafer‐scale semiconducting MoS2 monolayer...

As a promising building block of the emerging neuromorphic computing hardware, memristive structures with multi‐functionalities are highly desired to implement diversified computing applications in a single device. However, the demonstration of such multi‐functional structures remains limited. In this work, an Ag/GeS/Pt‐based bifunctional memory st...

Nanostructuring of 2D MXene has promised as a non-noble electrocatalyst for hydrogen evolution reaction. Nevertheless, the insufficient density and activity of active sites on its basal plane are largely limiting the catalytic performance. Here, we show that by tailoring the 2D MXene nanosheets into their 0D quantum dots (QDs), active sites from ed...

We design and synthesise a new high-entropy ceramic Hf 0.25 Zr 0.25 Ce 0.25 Y 0.125 Si 0.125 O 2-δ through a hybrid mixing of non-metal and metal atoms. First-principles calculations predict the thermal stability of the single-crystal phase at high temperatures. XRD and EDS mapping confirm a single cubic fluorite phase with a uniform elemental dist...

Inter-site interactions between single atom catalysts (SACs) in the high loading regime are critical to tuning the catalytic performance. However, the understanding on such interactions and their distance dependent effects remains elusive, especially for the heteronuclear SACs. In this study, we reveal the effects of the distance-dependent inter-si...

The integration of high-k dielectrics with two-dimensional (2D) semiconductors is a critical step towards high-performance nanoelectronics, which however remains challenging due to the high density of interface states and the damage to the monolayer 2D semiconductors. In this study, we propose a selective hydrogenation strategy to improve the inter...

Electrides intrinsically hold some unique properties arising from the anionic electrons such as the low work function from their loosely bound nature and extended distribution due to their absence of...

Solid sorbents for carbon dioxide (CO2) capture remains both a scientifically challenging and technologically important area of work. The use of the right material and the understanding of its microstructure...

Two-dimensional (2D) materials are sensitive to external stimuli. In this work, via a combined first-principles simulations and constrained random phase approximation, we report strain-induced multiple magnetic phase transitions in an...

Novel technologies and new materials are in high demand for future energy-efficient electronic devices to overcome the fundamental limitations of miniaturization of current silicon-based devices. Two-dimensional (2D) materials show promising applications in the next generation devices because they can be tailored on the specific property that a tec...

Complex oxide heterostructures such as the LaAlO3/SrTiO3 (LAO/STO) interface are paradigmatic platforms to explore emerging multidegree of freedom coupling and the associated exotic phenomena. In this paper, we reveal the effects of multiorbital and magnetic ordering on Rashba spin-orbit coupling (SOC) at the LAO/STO (001) interface. Based on first...

Few two-dimensional (2D) magnets have an intrinsic easy axis, which is essential for a long-range magnetic ordering for applications. Here, we show that without external magnetic fields, uniaxial strains can stabilize long-range ferromagnetic ordering in a 2D electrene, LaBr2, by effectively changing its magnetic anisotropy from the original easy p...

Two-dimensional (2D) chromium tellurides have attracted considerable research interest for their high Curie temperatures. Their magnetic properties have been found diverse in various experiments, the understanding of which however remains limited. In this work, we report that the magnetic ordering of ultrathin chromium tellurides is structure depen...

Tuning the bandgap of nanoporous graphene is desirable for applications such as the charge transport layer in organic-hybrid devices. The holy grail in the field is the ability to synthesize 2D nanoporous graphene with variable pore sizes, and hence tunable band gaps. Herein, the on-surface synthesis of nanoporous graphene with variable bandgaps is...

Lieb lattice, a two-dimensional edge-centered square lattice, has attracted considerable interest due to its exotic electronic and topological properties. Although various optical and photonic Lieb lattices have been experimentally demonstrated, it remains challenging for an electronic Lieb lattice to be realized in real material systems. Here, bas...

The realization of long-range magnetic ordering in 2D systems can potentially revolutionize next-generation information technology. Here, the successful fabrication of crystalline Cr3Te4 monolayers with room temperature (RT) ferromagnetism is reported. Using molecular beam epitaxy, the growth of 2D Cr3Te4 films with monolayer thickness is demonstra...

Two-dimensional (2D) chromium tellurides have attracted considerable research interest for their high Curie temperatures. Their magnetic properties have been found diverse in various experiments, the understanding of which however remains limited. In this work, we report that the magnetic ordering of ultrathin chromium tellurides is structure depen...

In this study, a FeCo [email protected] carbon yolk-shell nanoreactors (ANCYNs) was synthesized through the confinement pyrolysis of the polydopamine (PDA)-coated Fe/Co Prussian blue analogs (PBAs). The PDA-derived carbon shell formed preferentially via pyrolysis is of relevance to (i) protecting the framework structure from collapsing, (ii) increa...

Metal-semiconductor diodes constructed from two-dimensional (2D) van der Waals heterostructures show excellent gate electrostatics and a large built-in electric field at the tunnel junction, which can be exploited to make highly sensitive photodetector. Here we demonstrate a metal-semiconductor photodiode constructed by the monolayer graphene (Gr)...

The unique magnetic, electronic and optical features derived from their unpaired electrons have made radical polymers an attractive material platform for various applications. Here, we report solution-processable radical polymer membranes with multi-level porosities and study the impact of free radicals on important membrane separation processes in...

Achievement of large-size (1 × 1 cm²) freestanding strongly correlated perovskite SrTiO3 films is demonstrated by Haijiao Harsan Ma and co-workers in article number 2100025. Two emergent photoluminescence peaks are observed at ≈2.4 eV (green) and ≈1.8 eV (red) which are absent in its 3D bulk form or as-grown films unexfoliated. The green peak origi...

Understanding the energy alignment of electronic bands, which originate from ultrathin MoS2 layers and metal electrodes attached to them, is crucial for the design of MoS2-based electronic devices. We have applied internal photoemission spectroscopy (IPE) to analyze this alignment. We demonstrate that IPE can yield the barrier heights in the metal/...

The realization of long-range magnetic ordering in two-dimensional (2D) systems can potentially revolutionize next-generation information technology. Here, we report the successful fabrication of crystalline Cr3Te4 monolayers with room temperature ferromagnetism. Using molecular beam epitaxy, the growth of 2D Cr3Te4 films with monolayer thickness i...

The complex oxide heterostructures such as LaAlO3/SrTiO3 (LAO/STO) interface are paradigmatic platforms to explore emerging multi-degrees of freedom coupling and the associated exotic phenomena. In this study, we reveal the effects of multiorbital and magnetic ordering on Rashba spin-orbit coupling (SOC) at the LAO/STO (001) interface. Based on fir...

Exploring the thickness-dependent electronic properties of ultrathin transition metal dichalcogenides is crucial for novel optoelectronic devices. Particularly important is experimental information regarding the bandgap width. This information is scarce and often inconsistent among the several measurement techniques that were employed for this task...

Recently, electron correlation has been shown to play an important role in unconventional plasmon generation in highly correlated electron systems. Electrons in topological insulators, on the other hand, are massless and insensitive to nonmagnetic scattering due to their protection by time-reversal symmetry, which makes these materials appealing pl...

Mid-infrared (MIR) photonics has attracted tremendous interest because of its broad applications at atmospheric windows. In this work, we report high-performance MIR photonics based on large-scale and good-quality monolayer molybdenum disulfide (MoS 2 ). The open-aperture Z-scan measurement on the nonlinear saturable absorption features shows that...

In article number 2002704, Henry Medina, Ming Yang, Shijie Wang, Dongzhi Chi, and co‐workers report a ReRAM cell with outstanding cumulative probabilities using a MoS2/polymer heterostructure. Moreover, the high resistance state is determined to be an excellent source of multistate randomness. Thus, a process for the production of high‐performance...

Optical wavefront engineering has been rapidly developing in fundamentals from phase accumulation in the optical path to the electromagnetic resonances of confined nanomodes in optical metasurfaces. However, the amplitude modulation of light has limited approaches that usually originate from the ohmic loss and absorptive dissipation of materials. H...

Similar to placing a carpet on a staircase, terraced graphene is formed by stacking a layer of graphene on an atomically terraced substrate. This leads to topographic corrugations and charge puddles in the terraced graphene. In the presence of a magnetic field, its resistance can change as high as 5000% at room temperature, paving a route for extre...

Manipulation of charge localization in optimally doped copper oxide (cuprate) thin‐films via interfacial hybridization is reported by Xinmao Yin, Andrivo Rusydi, Andrew T. S. Wee, and co‐workers in article number 2000153. The appearance of a new high‐energy plasmon is further investigated. Unravelling the underlying mechanism provides important clu...

Resistive random-access memories (ReRAMs) based on transition metal dichalcogenide layers are promising physical sources for random number generation (RNG). However, most ReRAM devices undergo performance degradation from cycle to cycle, which makes preserving a normal probability distribution during operation a challenging task. Here, ReRAM device...

The development of infrared photodetectors is mainly limited by the choice of available materials and the intricate crystal growth process. Moreover, thermally activated carriers in traditional III–V and II–VI semiconductors enforce low operating temperatures in the infrared photodetectors. Here we demonstrate infrared photodetection enabled by int...

Disorder‐induced magnetoresistance (MR) effect is quadratic at low perpendicular magnetic fields and linear at high fields. This effect is technologically appealing, especially in 2D materials such as graphene, since it offers potential applications in magnetic sensors with nanoscale spatial resolution. However, it is a great challenge to realize a...

The atomically thickness of two-dimensional materials (2D) makes their physical and chemical properties vulnerable to external influence. In this study, we show that the electronic and optical properties of MoS2 monolayer can be tuned by the substrates (BN, g-GeC, and graphite). Based on the first-principles calculations with the GW and GW plus Bat...

Charge localization is critical to the control of charge dynamics in systems such as perovskite solar cells, organic‐, and nanostructure‐based photovoltaics. However, the precise control of charge localization via electronic transport or defect engineering is challenging due to the complexity in reaction pathways and environmental factors. Here, ch...

We formulate the effective Hamiltonian of Rashba spin-orbit coupling (RSOC) in $\mathrm{LaAlO_3/SrTiO_3}$ (LAO/STO) heterostructures. We derive analytical expressions of properties, e.g., Rashba parameter, effective mass, band edge energy and orbital occupancy, as functions of material and tunable heterostructure parameters. While linear RSOC is do...

Two-dimensional (2D) materials with intrinsically active basal planes are promising alternative catalysts to the Pt-group noble metals for large-scale hydrogen production. Herein, we perform a comprehensive screening of the 2D materials database (2DMatPedia) to identify such 2D catalysts for hydrogen evolution reaction (HER). Using the differential...

It is increasingly important to understand and study materials for removal of carbon dioxide (CO2) or other harmful gases for both industrial and commercial uses. In this work, we present pioneering work in studying how defects affect the sorption performance of Molybdenum (Mo) oxide. Using a unique thin film approach, we are able to study the chem...