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| Open AccessRevealing hidden spin polarization in centrosymmetric van der Waals materials on ultrafast timescales
A major challenge for spin-based information technologies is the generation of spin polarization in otherwise nonmagnetic materials. Here, Arnoldi et al. demonstrate how ultrafast laser excitations can be used to generate spin polarization in a fullerene/tungsten diselenide heterostructure.
- B. Arnoldi
- , S. L. Zachritz
- & B. Stadtmüller
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Article
| Open AccessVisualizing a single wavefront dislocation induced by orbital angular momentum in graphene
Phase singularities are intimately related to orbital angular momentum. Direct local imaging of orbital angular momentum effects at the nanoscale remains challenging. Here, the authors demonstrate via scanning tunnelling microscopy that inter-orbital angular momentum scatterings induced by asymmetric potentials can modulate the phase singularities and induce single-wavefront dislocations.
- Yi-Wen Liu
- , Yu-Chen Zhuang
- & Lin He
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Article
| Open AccessCollapse of carbon nanotubes due to local high-pressure from van der Waals encapsulation
vdW assembly of low-dimensional materials has proven the capability of creating structures with on-demand properties. Here, the authors report on the structural collapse of CNTs in conjunction with a metal-semiconductor junction induced by the VdW encapsulation.
- Cheng Hu
- , Jiajun Chen
- & Zhiwen Shi
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Article
| Open AccessFlower-shaped 2D crystals grown in curved fluid vesicle membranes
Thin crystals grown on rigid spherical templates of increasing curvature exhibit increased protrusions. Here, the authors demonstrate the opposite curvature effect on the morphology of molecularly thin crystals grown within elastic fluid membranes, like those of biological cells.
- Hao Wan
- , Geunwoong Jeon
- & Maria M. Santore
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Article
| Open AccessAtomic-scale observation of localized phonons at FeSe/SrTiO3 interface
The authors characterize the phonon modes at the FeSe/SrTiO3 interface with atomically resolved electron energy loss spectroscopy and correlate them with accurate atomic structure in an electron microscope. They find several phonon modes highly localized at the interface, one of which engages in strong interactions with the electrons in FeSe.
- Ruochen Shi
- , Qize Li
- & Peng Gao
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Article
| Open AccessFabrication-induced even-odd discrepancy of magnetotransport in few-layer MnBi2Te4
MnBi2Te4 is an antiferromagnetic topological insulator. This combination of magnetic ordering and topological properties has resulted in intense interest, however, like many van der Waals materials, experimental results are hampered by fabrication difficulties. Here, Li, Wang, Lian et al. show that the fabrication process itself can result in mismatched thickness dependence of magneto-transport measurements. ‘
- Yaoxin Li
- , Yongchao Wang
- & Chang Liu
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Article
| Open AccessAtomic-scale visualization of the interlayer Rydberg exciton complex in moiré heterostructures
Recently, Rydberg excitons have been demonstrated in transition metal dichalcogenide moire superlattices. Here, using atomic-scale imaging, the authors observe Rydberg structure and moire periodicity of ground-state interlayer excitons in a monolayer YbCl3 on highly oriented pyrolytic graphite.
- Meng Zhao
- , Zhongjie Wang
- & Chunlei Gao
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Article
| Open AccessElectronic inhomogeneity and phase fluctuation in one-unit-cell FeSe films
The authors study monolayer FeSe via scanning tunneling microscopy and simultaneous micron-scale-probe-based transport. They observe distinct superconducting phases in domains and on boundaries between domains, with different superconducting gaps and pairing temperatures.
- Dapeng Zhao
- , Wenqiang Cui
- & Qi-Kun Xue
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Article
| Open AccessControlled condensation by liquid contact-induced adaptations of molecular conformations in self-assembled monolayers
Surface condensation is predetermined and is typically adjusted by chemical or topographical surface modification. Here, the authors report on a strategy to control the surface condensation behavior by adjusting molecular conformations in self-assembled monolayers.
- Guoying Bai
- , Haiyan Zhang
- & Yufeng Liu
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Article
| Open AccessLight-induced giant enhancement of nonreciprocal transport at KTaO3-based interfaces
Optical control is an alternative pathway to boost nonlinear transport in noncentrosymmetric systems. Here, the authors observe a light-induced giant enhancement of nonreciprocal transport coefficient as high as 105 A−1 T−1 at KTaO3-based Rashba interfaces.
- Xu Zhang
- , Tongshuai Zhu
- & Xuefeng Wang
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Article
| Open AccessSwitching the spin cycloid in BiFeO3 with an electric field
Previous understanding of the coupling between ferroelectric structure and magnetic texture in BiFeO3 has relied on mesoscale measurements. Here, the authors image coupling directly, showing a complex spin cycloid controlled with electric field.
- Peter Meisenheimer
- , Guy Moore
- & Ramamoorthy Ramesh
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Article
| Open AccessIntrinsic exchange biased anomalous Hall effect in an uncompensated antiferromagnet MnBi2Te4
Exchange bias occurs in a variety of magnetic materials and heterostructures. The quintessential example occurs in antiferromagnetic/ferromagnetic heterostructures and has been employed extensively in magnetic memory devices. Here, via a specific field training protocol, the authors demonstrate an exchange bias of up to 400mT in odd layered MnBi2Te4.
- Su Kong Chong
- , Yang Cheng
- & Kang L. Wang
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| Open AccessEnhancement of electrocatalysis through magnetic field effects on mass transport
Magnetic fields can enhance electrocatalysis, yet its effect on mass transport has been overlooked. Here, the authors track the motion induced on the electrolyte ions, demonstrating that mass transport effects can double the catalyst activity with low reactant availability, as in oxygen reduction.
- Priscila Vensaus
- , Yunchang Liang
- & Magalí Lingenfelder
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Article
| Open AccessTopological minibands and interaction driven quantum anomalous Hall state in topological insulator based moiré heterostructures
Moiré patterns have been experimentally observed in heterostructures comprised of topological insulator films. Here, the authors propose that topological insulator-based moiré heterostructures could be a host of isolated topologically non-trivial moiré minibands for the study of the interplay between topology and correlation.
- Kaijie Yang
- , Zian Xu
- & Chao-Xing Liu
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| Open AccessDeep-potential enabled multiscale simulation of gallium nitride devices on boron arsenide cooling substrates
Efficient heat dissipation is critical to optimize high-power devices. Here, the authors report high interfacial thermal conductance in GaN-BAs heterostructures and investigate the competition between grain size and boundary resistance by multiscale simulations.
- Jing Wu
- , E Zhou
- & Guangzhao Qin
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Article
| Open AccessThermodynamic driving forces in contact electrification between polymeric materials
Contact electrification is a widely observed phenomenon in nature and in materials. Here, the authors use molecular dynamics simulations to show the importance of thermodynamic driving forces in contact electrification in insulating materials.
- Hang Zhang
- , Sankaran Sundaresan
- & Michael A. Webb
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Article
| Open AccessDirect visualization of stacking-selective self-intercalation in epitaxial Nb1+xSe2 films
The interplay between stacking configurations and atom intercalation in van der Waals materials has been rarely characterized at the microscopic level. Here, the authors report an electron microscopy study of stacking-selective self-intercalation in Nb1+xSe2 films, showing potential for nanoscale engineering of electronic properties in van der Waals materials and devices.
- Hongguang Wang
- , Jiawei Zhang
- & Hidenori Takagi
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Article
| Open AccessControlled dissolution of a single ion from a salt interface
The strong ionic bond in salt is broken by electrostatic interactions with water, but direct observation at the level of a single ion is challenging. Here, the authors have visualized the preferential dissolution of an anion by manipulating a single water molecule.
- Huijun Han
- , Yunjae Park
- & Hyung-Joon Shin
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Article
| Open AccessQuantum spin liquid signatures in monolayer 1T-NbSe2
Recently, signatures of quantum spin liquid have been reported in monolayer transition metal dichalcogenides. Here the authors report evidence of such state in 1T-NbSe2 via the measurements of the Kondo effect in a 1T-1H heterostructure, further supported by measurements for magnetic molecules on 1T-NbSe2.
- Quanzhen Zhang
- , Wen-Yu He
- & Yeliang Wang
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Article
| Open AccessTheory of resonantly enhanced photo-induced superconductivity
The authors theoretically propose a simple microscopic mechanism for light-induced superconductivity based on a boson coupled to an electronic interband transition. The electron-electron attraction needed for the superconductivity can be resonantly amplified when the boson’s frequency is close to the energy difference between the two electronic bands. The model can be engineered using a 2D heterostructure.
- Christian J. Eckhardt
- , Sambuddha Chattopadhyay
- & Marios H. Michael
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Article
| Open AccessUnveiling diverse coordination-defined electronic structures of reconstructed anatase TiO2(001)-(1 × 4) surface
By measuring in energy, momentum and real space, the authors unveil diverse coordination environments and electronic structures on the reconstructed anatase TiO2(001), giving insights into its structure-property relationship with atomic precision.
- Xiaochuan Ma
- , Yongliang Shi
- & Bing Wang
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Article
| Open AccessElectrostatic potentials of atomic nanostructures at metal surfaces quantified by scanning quantum dot microscopy
Surface averaging techniques offer only limited access to the electrostatic potentials of nanostructures, which are determined by shape, material, and environment. Here, the authors quantify these potentials for gold and silver adatom chains, explaining the mechanisms of dipole formation.
- Rustem Bolat
- , Jose M. Guevara
- & Christian Wagner
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Article
| Open AccessInterfacial ice sprouting during salty water droplet freezing
The understanding of salty water droplet freezing is limited. The authors examine the formation of brine film on top of frozen salty droplets and discover a new ice crystal growth pattern sprouting from the bottom of the brine film.
- Fuqiang Chu
- , Shuxin Li
- & Nenad Miljkovic
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| Open AccessPushing the thinness limit of silver films for flexible optoelectronic devices via ion-beam thinning-back process
The use of thin silver films with nanometric thickness for optoelectronic devices is essential for high transparency, flexibility, and electrical properties. Ma et al. report a thinning-back process with a flood ion beam, to further reduce film thickness down to 4.5 nm.
- Dongxu Ma
- , Ming Ji
- & Huigao Duan
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| Open AccessThree-dimensional magnetic nanotextures with high-order vorticity in soft magnetic wireframes
The spin texture of a magnetic system can host a variety of topological spin textures, the most famous of these being skyrmions. Here, Volkov et al demonstrate higher order vorticity in magnetic wireframe nanostructures and introduce a general protocol for the creation of arbitrary numbers of vortices and antivortices in such wireframe structures.
- Oleksii M. Volkov
- , Oleksandr V. Pylypovskyi
- & Denys Makarov
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| Open AccessObservation of the nonanalytic behavior of optical phonons in monolayer hexagonal boron nitride
Here, the authors use high-resolution electron energy-loss spectroscopy to study the phonon dispersion of monolayer hexagonal boron nitride. They observe that the longitudinal optical (LO) and transverse optical (TO) phonons at the Brillouin zone centre exhibit no energy splitting, contrary to the conventional LO-TO splitting seen in bulk materials.
- Jiade Li
- , Li Wang
- & Xuetao Zhu
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Article
| Open AccessFerromagnetism on an atom-thick & extended 2D metal-organic coordination network
Despite having all the ingredients required for the formation of two-dimensional ferromagnetism, achieving such a magnetic state in atomically thin metal-organic coordination networks has proved to be a persistent challenge. Here, Lobo-Checa et al demonstrate 2Dferromagnetism in a self-assembled network, exhibiting coercive fields over 2 Tesla and a Curie temperature of 35K.
- Jorge Lobo-Checa
- , Leyre Hernández-López
- & Fernando Bartolomé
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Article
| Open AccessDisentangling the multiorbital contributions of excitons by photoemission exciton tomography
Understanding excitonic optical excitations is integral to improving optoelectronic and photovoltaic semiconductor devices. Here, Bennecke et al. use photoemission exciton tomography to unravel the multiorbital electron and hole contributions of entangled excitonic states in the prototypical organic semiconductor C60.
- Wiebke Bennecke
- , Andreas Windischbacher
- & Stefan Mathias
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| Open AccessEngineering surface dipoles on mixed conducting oxides with ultra-thin oxide decoration layers
Improving materials for energy devices relates to an optimisation of their surfaces. Here authors show that surface modification with ultrathin oxide layers allows for a tailoring of the surface dipole and the work function of mixed ionic and electronic conducting oxides.
- Matthäus Siebenhofer
- , Andreas Nenning
- & Markus Kubicek
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| Open AccessProgrammable nanowrinkle-induced room-temperature exciton localization in monolayer WSe2
Here, the authors report on the fabrication of strained wrinkles in monolayer WSe2 by placing the material on Au nanoconical substrates. They investigate the correlation between topographical stress factors and localised, quantum-dot-like photoluminescence emission.
- Emanuil S. Yanev
- , Thomas P. Darlington
- & P. James Schuck
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Article
| Open AccessAchieving environmental stability in an atomically thin quantum spin Hall insulator via graphene intercalation
Topological states in atomically thin quantum spin Hall insulators suffer from instability against environmental factors. Here, the authors devise a strategy to preserve topologically protected states in monolayer indenene through graphene intercalation.
- Cedric Schmitt
- , Jonas Erhardt
- & Ralph Claessen
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Article
| Open AccessEndotaxial stabilization of 2D charge density waves with long-range order
Stabilizing charge density wave states in low-dimensional systems is challenging. Here, the authors stabilize an ordered incommensurate charge density wave at elevated temperatures via endotaxial synthesis of TaS2 polytype heterostructures, where charge density wave layers are encapsulated within metallic layers.
- Suk Hyun Sung
- , Nishkarsh Agarwal
- & Robert Hovden
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Article
| Open AccessSurface triggered stabilization of metastable charge-ordered phase in SrTiO3
Charge order has been typically reported in doped systems with high d-electron occupancy. Here the authors demonstrate a charge-ordered insulating state in a La-doped SrTiO3 epitaxial film which has the lowest d-electron occupancy and attribute it to surface distortion that favours electron-phonon coupling.
- Kitae Eom
- , Bongwook Chung
- & Jaichan Lee
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Article
| Open AccessRealization of large-area ultraflat chiral blue phosphorene
Blue phosphorene (BlueP) is a 2D phosphorus allotrope predicted to host Dirac fermions and other interesting electronic properties. Here, the authors report the growth of large-area BlueP films with ordered chiral nanostructures on Cu(111) substrates, expanding the range of its potential applications.
- Ye-Heng Song
- , M. U. Muzaffar
- & Zhenyu Zhang
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Article
| Open AccessIntrinsic supercurrent non-reciprocity coupled to the crystal structure of a van der Waals Josephson barrier
J.-K. Kim et al. study vertical Josephson junctions where the weak link is Td-WTe2 and the superconductor is NbSe2. The use of an inversion-symmetry-breaking Td-WTe2 weak link allows the authors to demonstrate the intrinsic origin of the observed Josephson non-reciprocity in these devices.
- Jae-Keun Kim
- , Kun-Rok Jeon
- & Stuart S. P. Parkin
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Article
| Open AccessPrinted smart devices for anti-counterfeiting allowing precise identification with household equipment
The authors introduce a flexible laser printing method for synthesizing integrated optical and electric Physical Unclonable Functions (PUFs). The PUF devices can be read out by simple household equipment and show high uniqueness and stability.
- Junfang Zhang
- , Rong Tan
- & Felix F. Loeffler
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Article
| Open AccessDual Higgs modes entangled into a soliton lattice in CuTe
The Higgs mode in condensed matter physics refers to the oscillations of the amplitude of the order parameter, and single Higgs modes have been studies in various systems. Here the authors report real-space observation of two coupled Higgs modes in a 1D charge density wave phase of CuTe.
- SeongJin Kwon
- , Hyunjin Jung
- & Han Woong Yeom
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Article
| Open AccessAtomic-scale manipulation of polar domain boundaries in monolayer ferroelectric In2Se3
Here, the authors realize controllable manipulation of polar domain boundaries in a two-dimensional ferroelectric material In2Se3. It reveals the origin of distinct behaviors for different domain boundaries in combination with density functional theory calculations.
- Fan Zhang
- , Zhe Wang
- & Chenggang Tao
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Article
| Open AccessInvestigating the role of undercoordinated Pt sites at the surface of layered PtTe2 for methanol decomposition
Methanol on under-coordinated Pt sites at surface Te vacancies on layered PtTe2 decomposes at a probability >90 % which ultimately produces gaseous molecular hydrogen, methane, water and formaldehyde.
- Jing-Wen Hsueh
- , Lai-Hsiang Kuo
- & Meng-Fan Luo
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Article
| Open AccessLow-temperature grapho-epitaxial La-substituted BiFeO3 on metallic perovskite
In the field of multiferroic thin films, attaining low-temperature epitaxy has been a long-standing problem. In this work, authors propose a pathway to significantly reduce the BiFeO3 thin film growth temperature using the BaBiPbO3 template.
- Sajid Husain
- , Isaac Harris
- & Ramamoorthy Ramesh
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Article
| Open AccessDirect observation of strong surface reconstruction in partially reduced nickelate films
Surface polarity affects the electronic and structural properties of oxide thin films through electrostatic effects, which is challenging to control. Here, the authors probe the tunable surface polarity at the atomic scale.
- Chao Yang
- , Rebecca Pons
- & Peter A. van Aken
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Article
| Open AccessUnderstanding the light induced hydrophilicity of metal-oxide thin films
Light-induced hydrophilicity of TiO2 and ZnO surfaces rely on the same physics and involve excitation of electron-hole pairs. Here, the authors propose and test a model for the photowetting of TiO2 and ZnO thin films. The results suggest design rules for materials exhibiting photocatalytic wetting.
- Rucha Anil Deshpande
- , Jesper Navne
- & Rafael Taboryski
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Article
| Open AccessA broad-spectrum gas sensor based on correlated two-dimensional electron gas
Gas sensors typically detect only few specific gases; the authors show a broad-spectrum sensor based on correlated 2-dimensional electron gas (C-2DEG), which detects various gases quantitatively and measures partial pressures, through a purely physical mechanism.
- Yuhao Hong
- , Long Wei
- & Zhaoliang Liao
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Article
| Open AccessHow frictional slip evolves
Conventionally, a continuous motion or “dynamic friction” is expected to take place after the initial rupture under friction. Here, the authors perform direct measurement of real contact and slip at the frictional interface and show that the secondary rupture takes place after each initial rupture.
- Songlin Shi
- , Meng Wang
- & Jay Fineberg
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Article
| Open AccessOn-chip phonon-magnon reservoir for neuromorphic computing
Developing efficient reservoir computing hardware that combines optically excited acoustic and spin waves with high spatial density remains a challenge. In this work, the authors propose a design capable of recognizing visual shapes drawn by a laser within remarkably confined spaces, down to 10 square microns.
- Dmytro D. Yaremkevich
- , Alexey V. Scherbakov
- & Manfred Bayer
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Article
| Open AccessLow-dimensional heat conduction in surface phonon polariton waveguide
Heat conduction in solids is known to be contributed by phonons and electrons. Here, authors observe enhanced and non-diffusive thermal conductance mediated by surface phonon polaritons in polar dielectric nanoribbon waveguides.
- Yu Pei
- , Li Chen
- & Renkun Chen
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Article
| Open AccessRecord high room temperature resistance switching in ferroelectric-gated Mott transistors unlocked by interfacial charge engineering
Ferroelectric transistors are promising building blocks for developing energy-efficient memory and logic applications. Here, the authors report a record high 300 K resistance on-off ratio achieved in ferroelectric-gated Mott transistors by exploiting a charge transfer layer to tailor the channel carrier density and mitigate the ferroelectric depolarization effect.
- Yifei Hao
- , Xuegang Chen
- & Xia Hong
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Article
| Open AccessIncommensurate grain-boundary atomic structure
Grain boundary atomic structures of crystalline materials have long been believed to be commensurate with the crystal periodicity of the adjacent crystals. Here, the authors discover an incommensurate grain boundary structure based on direct observations and theoretical calculations.
- Takehito Seki
- , Toshihiro Futazuka
- & Naoya Shibata
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Article
| Open AccessTwo-dimensional heavy fermion in a monoatomic-layer Kondo lattice YbCu2
Examples of 2D heavy-fermion materials are rare, and the details of their electronic structure have remained elusive. Here, Nakamura et al. report the synthesis and angle-resolved photoemission spectroscopy measurements of a monolayer Kondo lattice, YbCu2, on a Cu(111) surface with an estimated coherence temperature of 30 K.
- Takuto Nakamura
- , Hiroki Sugihara
- & Shin-ichi Kimura