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| Open AccessMetavalently bonded tellurides: the essence of improved thermoelectric performance in elemental Te
Doping is a common strategy to improve thermoelectric performance yet limited to the solid solubility of dopants. Here, the authors find that forming metavalently bonded precipitates is key to property enhancement in Te rather than modifying the matrix lattice.
- Decheng An
- , Senhao Zhang
- & Yuan Yu
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Article
| Open AccessGiant Faraday rotation in atomically thin semiconductors
Here, the authors perform Faraday rotation spectroscopy around the excitonic transitions in hBN-encapsulated WSe2 and MoSe2 monolayers, and interlayer excitons in MoS2 bilayers. They measure a large Verdet constant - 1.9 × 107 deg T−¹cm−¹ for monolayers, and attribute it to the giant oscillator strength and high g-factor of the excitons.
- Benjamin Carey
- , Nils Kolja Wessling
- & Ashish Arora
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Article
| Open AccessPushing thermal conductivity to its lower limit in crystals with simple structures
The pursuit of materials with low heat conductivity is vital for numerous applications. Here, the authors find AgTlI2 show low heat conductivity of 0.25 W/mK at room temperature, discussing its thermal transport mechanisms.
- Zezhu Zeng
- , Xingchen Shen
- & Yue Chen
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Article
| Open AccessEmissive brightening in molecular graphene nanoribbons by twilight states
The authors demonstrate that the band structure of graphene nanoribbons is modulated by cove edges, brightening the luminescence 4-fold via emission from otherwise dark twilight states. High spectral resolution of the optical response reveals strong vibron-electron coupling
- Bernd K. Sturdza
- , Fanmiao Kong
- & Robin J. Nicholas
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Article
| Open AccessCharge state-dependent symmetry breaking of atomic defects in transition metal dichalcogenides
The microscopic structure of quantum defects in 2D materials is crucial to understand their optical properties and spin-photon interface. Here, the authors report the direct imaging of charge state-dependent symmetry breaking of sulfur vacancies and rhenium dopants in 2D MoS2, showing evidence of a Jahn-Teller effect.
- Feifei Xiang
- , Lysander Huberich
- & Bruno Schuler
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| Open AccessSpin-orbital Jahn-Teller bipolarons
The interplay between electron-phonon and spin-orbit interactions has led to the concept of a spin-orbit polaron. Here the authors show that such a regime is realized in a spin-orbit-coupled Mott insulator, leading to a new polaron quasiparticle, and study its effect on the Mott metal-insulator transition.
- Lorenzo Celiberti
- , Dario Fiore Mosca
- & Cesare Franchini
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Article
| Open AccessElectron/infrared-phonon coupling in ABC trilayer graphene
Via Raman and infrared spectroscopy measurements, X. Zan et al. find that rhombohedral ABC trilayer graphene has stronger electron/infrared-phonon coupling than Bernal ABA trilayer graphene.
- Xiaozhou Zan
- , Xiangdong Guo
- & Guangyu Zhang
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Article
| Open AccessReal-time two-axis control of a spin qubit
Real-time adaptive control of a qubit has been demonstrated but limited to single-axis Hamiltonian estimation. Here the authors implement two-axis control of a singlet-triplet spin qubit with two fluctuating Hamiltonian parameters, resulting in improved quality of coherent oscillations.
- Fabrizio Berritta
- , Torbjørn Rasmussen
- & Ferdinand Kuemmeth
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Article
| Open AccessNon-volatile electrical polarization switching via domain wall release in 3R-MoS2 bilayer
Sliding ferroelectricity occurs in stacks of van der Waals materials. Depending on the particular stacking, the system can host a spontaneous polarization, and under an applied electric field, polarization domain walls will propagate transverse to the electric field. Here, Yang et al use an optical approach to directly observe this sliding of domain walls in bilayer MoS2.
- Dongyang Yang
- , Jing Liang
- & Ziliang Ye
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Article
| Open AccessSpin-EPR-pair separation by conveyor-mode single electron shuttling in Si/SiGe
Electron charge and spin shuttling is a promising technique for connecting distant spin qubits. Here the authors use conveyor-mode shuttling to achieve high-fidelity transport of a single electron spin in Si/SiGe by separation and rejoining of two spin-entangled electrons across a shuttling distance of 560 nm.
- Tom Struck
- , Mats Volmer
- & Lars R. Schreiber
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Article
| Open AccessSteep-slope vertical-transport transistors built from sub-5 nm Thin van der Waals heterostructures
2D vertical transport transistors (VTFETs) may promote the downscaling of electronic devices, but their performance is usually restricted by the thermionic limit. Here, the authors report the realization of short-channel steep-slope VTFETs based on MoS2/MoTe2 heterojunctions integrated with resistance threshold switching cells.
- Qiyu Yang
- , Zheng-Dong Luo
- & Genquan Han
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Article
| Open AccessDeceptive orbital confinement at edges and pores of carbon-based 1D and 2D nanoarchitectures
The apparent electronic confinement at nanographene boundaries in scanning tunneling microscopy/spectroscopy is often misinterpreted. Here, the authors explain this phenomenon in terms of the decay of frontier orbitals and confinement at the edges of graphene nanoribbons and pores in nanoporous graphene.
- Ignacio Piquero-Zulaica
- , Eduardo Corral-Rascón
- & Johannes V. Barth
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Article
| Open AccessLocalisation-to-delocalisation transition of moiré excitons in WSe2/MoSe2 heterostructures
Stacking two-dimensional crystals creates a moiré superpotential that confines excitons. Here, temperature-/time- and magnetic field-dependent optical spectroscopy allows identifying the conditions under which excitons escape from the moiré potential
- Elena Blundo
- , Federico Tuzi
- & Antonio Polimeni
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Article
| Open AccessApproaching a fully-polarized state of nuclear spins in a solid
Highly polarized nuclear spins can supress decoherence of electron spin qubits, but this requires near-unity polarization. Here the authors implement a protocol combining optical excitation and fast carrier tunnelling to achieve nuclear spin polarizations above 95% in GaAs quantum dots on a timescale of 1 minute.
- Peter Millington-Hotze
- , Harry E. Dyte
- & Evgeny A. Chekhovich
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Article
| Open AccessDirect bandgap emission from strain-doped germanium
The authors proposed a Silicon technology-compatible approach to convert Germanium from an indirect bandgap to a direct bandgap via doping. This is done to expand the lattice to produce tunable effective tensile strain, aiming towards the on-chip light sources.
- Lin-Ding Yuan
- , Shu-Shen Li
- & Jun-Wei Luo
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Article
| Open AccessResolving electron and hole transport properties in semiconductor materials by constant light-induced magneto transport
Here, the authors introduce a constant light-induced magneto-transport method which seamlessly integrates light, current, and a magnetic field to characterize electron and hole properties across an expansive array of materials.
- Artem Musiienko
- , Fengjiu Yang
- & Antonio Abate
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Article
| Open AccessSpin relaxation of electron and hole polarons in ambipolar conjugated polymers
Spin and charge dynamics are inevitably linked, the study of the one often illuminating the other. Here, the authors study spin relaxation in ambipolar polymers and, backed by simulations, show how charge dynamics and wavefunction localization together set relaxation times up to room temperature.
- Remington L. Carey
- , Samuele Giannini
- & Henning Sirringhaus
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Article
| Open AccessHyperbolic exciton polaritons in a van der Waals magnet
Hyperbolic exciton polaritons (HEPs) are anisotropic light-matter excitations with promising applications, but their steady-state observation is challenging. Here, the authors report experimental evidence of HEPs in a van der Waals magnet, CrSBr, via cryogenic infrared near-field microscopy.
- Francesco L. Ruta
- , Shuai Zhang
- & D. N. Basov
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| Open AccessPhase-dependent Andreev molecules and superconducting gap closing in coherently-coupled Josephson junctions
S. Matsuo et al. report tunneling spectroscopy measurements on a device consisting of two Josephson junctions (JJ) sharing a single superconducting electrode. In isolation, each JJ would host an Andreev bound state (ABS). In their coherently-coupled JJs, the authors report the formation of an Andreev molecule due to hybridization of the two ABSs.
- Sadashige Matsuo
- , Takaya Imoto
- & Seigo Tarucha
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Article
| Open AccessLarge scale purification in semiconductors using Rydberg excitons
Charged impurities are a major source of charge noise in semiconductors. Here, using pump-probe time-resolved relative transmission measurements on cuprous oxide, the authors demonstrate a strategy for mitigating charged impurities by injection and subsequent breakdown of Rydberg excitons.
- Martin Bergen
- , Valentin Walther
- & Marc Aßmann
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Article
| Open AccessCoherent charge oscillations in a bilayer graphene double quantum dot
Graphene quantum dots promise applications for spin and valley qubits; however a demonstration of phase coherent oscillations has been lacking. Here the authors report coherent charge oscillations and measurements of coherence times in highly tuneable double quantum dots in bilayer graphene.
- K. Hecker
- , L. Banszerus
- & C. Stampfer
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Article
| Open AccessCryogenic multiplexing using selective area grown nanowires
The authors demonstrate a large ensemble of quantum dots which is characterized using a cryogenic multiplexer-demultiplexer circuit based on selective area growth nanowires, establishing the feasibility of scaling future quantum circuits.
- Dāgs Olšteins
- , Gunjan Nagda
- & Thomas S. Jespersen
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Article
| Open AccessBidirectional light-emitting diode as a visible light source driven by alternating current
The bidirectional light-emitting diode emits visible light regardless of the direction of current flow, leading to AC applications. This is made possible by the use of two oppositely oriented tunnel junctions that surround the active region.
- Mikołaj Żak
- , Grzegorz Muziol
- & Czesław Skierbiszewski
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Article
| Open AccessWide-temperature-range thermoelectric n-type Mg3(Sb,Bi)2 with high average and peak zT values
The utilization of Mg3(Sb,Bi)2 in thermoelectric devices is hindered by its low performance near room temperature. Here, authors report thermoelectric performance enhancement of Mg3(Sb,Bi)2 within a wide temperature range by incorporating metallic inclusions at grain boundaries. (279 in total)
- Jing-Wei Li
- , Zhijia Han
- & Jing-Feng Li
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Article
| Open AccessTime-domain observation of interlayer exciton formation and thermalization in a MoSe2/WSe2 heterostructure
Here, the authors use ultrafast transient absorption spectroscopy with a broadband white-light probe to simultaneously resolve interlayer charge transfer and interlayer exciton formation dynamics in a MoSe2/WSe2 heterostructure.
- Veronica R. Policht
- , Henry Mittenzwey
- & Stefano Dal Conte
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Article
| Open AccessLarge composite fermion effective mass at filling factor 5/2
The fractional quantum Hall state at the filling factor 5/2 has been intensively studied due to its predicted non-Abelian statistics. Petrescu et al. measure the composite fermion effective mass of this state and find that it is several times larger than that in the half-filled lowest Landau level.
- M. Petrescu
- , Z. Berkson-Korenberg
- & G. Gervais
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Article
| Open AccessObserving the universal screening of a Kondo impurity
Previous work on charge Kondo circuits, in which a spin is formed by two degenerate charge states of a metallic island, has been limited to transport measurements of multi-channel Kondo problems. Piquard et al. use thermodynamic measurements via a charge sensor to study the evolution of a single Kondo impurity.
- C. Piquard
- , P. Glidic
- & F. Pierre
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Article
| Open AccessSpin-filtered measurements of Andreev bound states in semiconductor-superconductor nanowire devices
Andreev bound states can form in hybrid semiconducting-superconducting devices and can mirror the experimental signatures of the much sought topologically non-trivial Majorana bound states. Here, van Driel, Wang and coauthors present a method of directly measuring the spin-polarized excitation spectrum of Andreev bound states.
- David van Driel
- , Guanzhong Wang
- & Tom Dvir
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Article
| Open AccessMicrowave-induced conductance replicas in hybrid Josephson junctions without Floquet—Andreev states
The authors study conductance replicas emerging under microwave irradiation in the tunnelling spectrum of Josephson junctions in InAs/Al heterostructures, focusing on distinguishing the signatures of Floquet-Andreev states (FASs) from those of photon-assisted tunneling (PAT). They establish that PAT largely dominates the response to microwave radiation in their device.
- Daniel Z. Haxell
- , Marco Coraiola
- & Fabrizio Nichele
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Article
| Open AccessThe squeezed dark nuclear spin state in lead halide perovskites
Nuclear spins in solid-state systems present a promising platform for quantum information applications. Here the authors report evidence of the long-predicted entangled dark nuclear spin state via optical polarization of localized hole spins coupled to the nuclear bath in a lead halide perovskite semiconductor.
- E. Kirstein
- , D. S. Smirnov
- & M. Bayer
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Article
| Open AccessDual-modal piezotronic transistor for highly sensitive vertical force sensing and lateral strain sensing
Developing mechanical sensors with two working modes for detecting vertical force and lateral strain is challenging. Here, Ge et al. report a piezotronic transistor with protrusions that enable dual-modal functionality and improve sensing performance.
- Rui Ge
- , Qiuhong Yu
- & Yong Qin
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Article
| Open AccessKapitza-resistance-like exciton dynamics in atomically flat MoSe2-WSe2 lateral heterojunction
Here, the authors use tip-enhanced photoluminescence spectroscopy to show a discontinuity of the exciton density distribution on each side of the interface of a MoSe2/WSe2 lateral heterostructure. They introduce the concept of ‘exciton Kapitza resistance’ by analogy with the interfacial thermal resistance known as ‘Kapitza resistance’.
- Hassan Lamsaadi
- , Dorian Beret
- & Jean-Marie Poumirol
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Article
| Open AccessInterlayer donor-acceptor pair excitons in MoSe2/WSe2 moiré heterobilayer
The nature of localized interlayer excitons (LIXs) in moiré superlattices is still elusive Here, the authors propose a donor-acceptor pair mechanism for LIXs in MoSe2/WSe2 heterobilayers.
- Hongbing Cai
- , Abdullah Rasmita
- & Weibo Gao
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Article
| Open AccessPhotoluminescence upconversion in monolayer WSe2 activated by plasmonic cavities through resonant excitation of dark excitons
Here, the authors perform statistical measurements on hundreds of plasmonic nano-cavities embedding WSe2 monolayers, and show the activation of anti-Stokes photoluminescence in WSe2 through resonant excitation of a dark exciton at room temperature.
- Niclas S. Mueller
- , Rakesh Arul
- & Jeremy J. Baumberg
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Article
| Open AccessInterplay of valley polarized dark trion and dark exciton-polaron in monolayer WSe2
Here, the authors observe that valley-polarized dark excitons in monolayer WSe2 show a distinct doping dependence when the carriers reach a critical density. This is indicative of the onset of strongly modified Fermi sea interactions.
- Xin Cong
- , Parisa Ali Mohammadi
- & Xiao-Xiao Zhang
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Article
| Open AccessUnexpected doping effects on phonon transport in quasi-one-dimensional van der Waals crystal TiS3 nanoribbons
Doping generally hinders phonon transport. Here, authors significantly increase the thermal conductivity of TiS3 nanoribbons through doping, originating from the intensified bonding strength along the molecular chain direction without distorting the one-dimensional structure induced by doped atoms.
- Chenhan Liu
- , Chao Wu
- & Yunfei Chen
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Article
| Open AccessControlling the propagation asymmetry of hyperbolic shear polaritons in beta-gallium oxide
Hyperbolic phonon polaritons occurring in anisotropic materials exhibit strong light confinement and propagation directionality. Matson et al. report real-space imaging and control of recently discovered hyperbolic shear phonon-polaritons in beta-Ga2O3, arising from symmetry breaking in the dielectric response.
- Joseph Matson
- , Sören Wasserroth
- & Joshua D. Caldwell
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Article
| Open AccessExtending the coherence of spin defects in hBN enables advanced qubit control and quantum sensing
Negatively-charged boron vacancy centers in hBN have short coherence times, hindering their potential as quantum sensors. By employing dynamical decoupling, the authors achieve an ensemble coherence time approaching the fundamental relaxation limit, enabling sensitive detection of MHz range electromagnetic fields.
- Roberto Rizzato
- , Martin Schalk
- & Dominik B. Bucher
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Article
| Open AccessUniversal radiation tolerant semiconductor
Here authors show that gamma/beta double polymorph Ga2O3 structures exhibit unprecedently high radiation tolerance accommodating disorder equivalent to hundreds of displacements per atom. Thus, such Ga2O3 structures benchmark a new class of radiation tolerant semiconductors.
- Alexander Azarov
- , Javier García Fernández
- & Andrej Kuznetsov
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Article
| Open AccessAn avalanche-and-surge robust ultrawide-bandgap heterojunction for power electronics
Avalanche and surge robustness are fundamental for power devices to survive overvoltage and overcurrent stresses in typical applications. Here, authors report NiO/Ga2O3 heterojunctions with smaller reverse recovery, higher switching speed, and a robustness competitive to that of conventional homojunctions.
- Feng Zhou
- , Hehe Gong
- & Jiandong Ye
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Article
| Open AccessProbing hyperbolic and surface phonon-polaritons in 2D materials using Raman spectroscopy
Hyperbolic phonon polaritons (HPhPs) in anisotropic van der Waals materials hold promise for nanophotonic applications, but their far-field characterization remains challenging. Here, the authors demonstrate the application of Raman spectroscopy in a backscattering configuration to determine the dispersion of HPhPs in thin GaSe crystals.
- Alaric Bergeron
- , Clément Gradziel
- & Sébastien Francoeur
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Article
| Open AccessExciton dissociation in 2D layered metal-halide perovskites
The photophysics of 2D layered Ruddlesden-Popper perovskites is still lively debated. Here, authors address the exciton stability of perovskites in form of film and single crystal by resonant injection of cold excitons and probe the exciton dissociation with femtosecond differential transmission.
- Angelica Simbula
- , Luyan Wu
- & Giovanni Bongiovanni
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Article
| Open AccessInterspecies exciton interactions lead to enhanced nonlinearity of dipolar excitons and polaritons in MoS2 homobilayers
In semiconductors, accessing nonlinear interactions between excitons strongly coupled to light will be key for quantum technologies. Here, in atomic bilayers of MoS2, new types of excitons are discovered showing strong inter-excitonic interactions.
- Charalambos Louca
- , Armando Genco
- & Alexander I. Tartakovskii
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Article
| Open AccessInteraction-driven transport of dark excitons in 2D semiconductors with phonon-mediated optical readout
Here, the authors demonstrate that dark excitons in two-dimensional transition metal dichalcogenides can diffuse over several micrometers, and prove that this repulsion-driven propagation is robust across non-uniform samples.
- Saroj B. Chand
- , John M. Woods
- & Gabriele Grosso
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Article
| Open AccessAsynchronous locking in metamaterials of fluids of light and sound
Exciton-polariton condensates are hybrid systems with nonlinear interactions. Here the authors demonstrate metamaterials with inter-site polariton coupling and asynchronous locking of light fluids from neighbor sites at the energy detuning.
- D. L. Chafatinos
- , A. S. Kuznetsov
- & A. Fainstein
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Article
| Open AccessEnabling metallic behaviour in two-dimensional superlattice of semiconductor colloidal quantum dots
Charge carrier transport in colloidal quantum dot assemblies is slow due to hopping transport nature. Here, the authors report the demonstration of gate-tuned metallic state in epitaxially-connected quantum dot superlattices by minimizing disorders.
- Ricky Dwi Septianto
- , Retno Miranti
- & Satria Zulkarnaen Bisri
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Article
| Open AccessRotational and dilational reconstruction in transition metal dichalcogenide moiré bilayers
Lattice reconstruction crucially influences the electronic properties of twisted van der Waals structures. Here, the authors report a quantitative characterization of the mechanical deformations occurring in small-angle twisted bilayers and heterobilayers of 2D semiconductors via interferometric 4D scanning transmission electron microscopy.
- Madeline Van Winkle
- , Isaac M. Craig
- & D. Kwabena Bediako
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Article
| Open AccessWigner-molecularization-enabled dynamic nuclear polarization
Wigner molecules, or correlated localized electron states, has been reported in semiconductor quantum dots, but their interaction with environment has been less explored. Here the authors use the spin multiplet structure of a three-electron Wigner molecule to enhance and control dynamic nuclear polarization.
- Wonjin Jang
- , Jehyun Kim
- & Dohun Kim
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Article
| Open AccessNuclear spin diffusion in the central spin system of a GaAs/AlGaAs quantum dot
Interaction between localized electron spins and nuclear spins causes shifts in nuclear spin energy levels, but how this affects nuclear spin diffusion in quantum dots is not fully understood. Here the authors show that the central electron accelerates nuclear spin diffusion in GaAs/AlGaAs quantum dots.
- Peter Millington-Hotze
- , Santanu Manna
- & Evgeny A. Chekhovich