Condensed-matter physics

  • Article
    | Open Access

    The honeycomb lattice with a spin-orbit interaction can give rise to exotic quantum states. With the measurements of bulk properties and inelastic neutron scattering, Lin et al demonstrate the existence of a field induced spin-disordered state in Na2Co2TeO6 and extend the Kitaev model to 3d system.

    • Gaoting Lin
    • , Jaehong Jeong
    •  & Jie Ma
  • Article
    | Open Access

    Graphene nanoribbons are potential systems for engineering topological phases of matter, but the pre-required gapped phases are difficult to find. Here, the authors show that chiral graphene nanoribbons undergo a transition from metallic to topological insulators, and then to trivial band insulators as they are narrowed down to nanometer widths.

    • Jingcheng Li
    • , Sofia Sanz
    •  & Jose Ignacio Pascual
  • Article
    | Open Access

    Resistive switching usually occurs by the formation of conducting filaments in the direction of current flow. Here the authors study an intriguing type of volatile metal-to-insulator resistive switching in (La,Sr)MnO3, which occurs by the formation of an insulating barrier perpendicular to the current.

    • Pavel Salev
    • , Lorenzo Fratino
    •  & Ivan K. Schuller
  • Article
    | Open Access

    Valley anisotropy is proposed theoretically to benefit the electrical transport of thermoelectric materials but it lacks experimental demonstration. Here, the authors demonstrate how to utilize the single anisotropic Fermi pocket in p-type Mg3Sb2 to enhance its thermoelectric properties.

    • Airan Li
    • , Chaoliang Hu
    •  & Tiejun Zhu
  • Article
    | Open Access

    Here, the authors report on evidence of an excitonic species formed by electrons in high-energy conduction band states with a negative effective mass, explaining previous observations of quantum interference phenomena in two-dimensional semiconductors.

    • Kai-Qiang Lin
    • , Chin Shen Ong
    •  & John M. Lupton
  • Article
    | Open Access

    Several hydrides have been observed high-Tc superconductivity under pressure, but a physical-chemical understanding of the properties enhancing Tc is still lacking. Here, the authors propose a magnitude named as networking value, combined with hydrogen fraction and the contribution of hydrogen to the density of states at Fermi level, can predict Tc of all hydrogen-based compounds with an accuracy of about 60 K.

    • Francesco Belli
    • , Trinidad Novoa
    •  & Ion Errea
  • Article
    | Open Access

    Magic-angle twisted bilayer graphene exhibits a quantum anomalous Hall effect at 3/4 filling; however, its mechanism is debated. Here, the authors show that such a phase can be realized in a lattice model of twisted bilayer graphene in the strong coupling limit, and interpret the results in terms of a topological Mott insulator phase.

    • Bin-Bin Chen
    • , Yuan Da Liao
    •  & Zi Yang Meng
  • Article
    | Open Access

    Strong light-matter coupling has been realized at the level of single atoms and photons throughout most of the electromagnetic spectrum, except for the THz range. Here, the authors report a THz-scale transport gap, induced by vacuum fluctuations in carbon nanotube quantum dot through the deep strong coupling of a single electron to a THz resonator.

    • F. Valmorra
    • , K. Yoshida
    •  & T. Kontos
  • Article
    | Open Access

    Transition metal kagome compounds have been shown to host flat bands in their bulk electronic spectrum. Here, using planar tunnelling spectroscopy supported by first-principles calculations, the authors report the signature of a novel type of flat band at the surface of antiferromagnetic kagome metal FeSn.

    • Minyong Han
    • , Hisashi Inoue
    •  & Joseph G. Checkelsky
  • Article
    | Open Access

    Optical excitation of transition metal dichalcogenide monolayers mostly generates excitons species with inherently short lifetime and spin/valley relaxation time. Here, the authors demonstrate efficient spin/valley optical pumping of resident electrons in n-doped WSe2 and WS2 monolayers.

    • Cedric Robert
    • , Sangjun Park
    •  & Xavier Marie
  • Article
    | Open Access

    Superconductivity in FeSe attracted great interests to understand the mechanism of high temperature superconductivity. Here, the authors report a pressure induced superconductivity with a highest Tc of ~9 K in MnSe.

    • T. L. Hung
    • , C. H. Huang
    •  & T. K. Lee
  • Article
    | Open Access

    Atomic monolayers of large-gap quantum spin Hall insulators are challenging to synthesize. Here, the authors realize massive Dirac fermions emerging from Bloch wave-function interference on a triangular lattice and achieve topologically non-trivial domains with unprecedented spatial extension.

    • Maximilian Bauernfeind
    • , Jonas Erhardt
    •  & Giorgio Sangiovanni
  • Article
    | Open Access

    Room-temperature exciton polaritons in a monolayer WS2 are shown to display strong motional narrowing of the linewidth and enhanced first-order coherence. They can propagate for tens of micrometers while maintaining partial coherence, and display signatures of ballistic (dissipationless) transport.

    • M. Wurdack
    • , E. Estrecho
    •  & E. A. Ostrovskaya
  • Article
    | Open Access

    Though non-Hermitian physics has contributed toward the advance of research in quantum, electronic and classical systems, previous work focused on zero- or one-dimensional systems. Here, the authors report higher-order non-Hermitian skin effects in a 2D acoustic higher-order topological insulator.

    • Xiujuan Zhang
    • , Yuan Tian
    •  & Yan-Feng Chen
  • Article
    | Open Access

    Toroidal moments arise from vortex like spin arrangements. These moments can then interact, giving rise to ferri- or ferro-toroidal order, though controlling such order is difficult. Here, the authors demonstrate a ferri-toroidal state in BaCoSiO4, which under an applied magnetic field exhibits multiple toroidal and metamagnetic transitions.

    • Lei Ding
    • , Xianghan Xu
    •  & Huibo Cao
  • Article
    | Open Access

    Van der Waals structures provide a new platform to explore novel physics of superconductor/ferromagnet interfaces. Here, NbSe2 Josephson junction with Cr2Ge2Te6 enables non-trivial Josephson phase by spin-dependent interaction, boosting the study of superconducting states with spin-orbit coupling and phase-controlled quantum electronic device.

    • H. Idzuchi
    • , F. Pientka
    •  & P. Kim
  • Article
    | Open Access

    Anisotropic spin S >1/2 quantum magnets can have multiple low energy modes. In this manuscript, the authors study the interaction of such low energy modes in the S = 1 antiferromagnet Ba2FeSi2O7 by combining neutron scattering measurements with an SU(3) generalization of the 1/S expansion.

    • Seung-Hwan Do
    • , Hao Zhang
    •  & Andrew D. Christianson
  • Article
    | Open Access

    Conventional quantum particles can break up into fractionalized excitations under the right conditions; however, their direct experimental observation is challenging. Here, the authors predict strong optical conductivity signatures of such excitations in the vicinity of a topological phase transition.

    • Yan-Cheng Wang
    • , Meng Cheng
    •  & Zi Yang Meng
  • Article
    | Open Access

    The inverse design of the material for given target property is challenging for glasses due to their disordered non-prototypical structure. Wang and Zhang propose a data-driven property oriented inverse approach for design of glassy materials with desired functionalities.

    • Qi Wang
    •  & Longfei Zhang
  • Article
    | Open Access

    Skyrmions are topological two-dimensional spin textures that in three-dimensional systems resemble strings or tubes. Here, using transmission electron microscopy Zheng et al observe the braiding of skyrmion strings in FeGe and predict this phenomenon for a large family of magnets.

    • Fengshan Zheng
    • , Filipp N. Rybakov
    •  & Rafal E. Dunin-Borkowski
  • Article
    | Open Access

    Previous work has shown that helical domain walls can form between states of different spin-polarization during a ferromagnetic spin transition in the fractional quantum Hall regime. Here, the authors study the transport through a single helical domain wall and find strong deviations from a simplified theory of weakly interacting edge channels.

    • Ying Wang
    • , Vadim Ponomarenko
    •  & Leonid P. Rokhinson
  • Article
    | Open Access

    Phase transition brings a plethora of exotic phenomena and intriguing effects such as spin and charge frustration. However, the phase transition order is not always explicit. Here, the authors discover phase transition frustration near a tricritical composition point in ferroelectric Pb(Zr,Ti)O3.

    • Xian-Kui Wei
    • , Sergei Prokhorenko
    •  & Zuo-Guang Ye
  • Article
    | Open Access

    The nonequilibrium regime provides an exciting frontier in the search for novel quantum phases of matter. Here, the authors show that optically driving a lightly-doped semiconductor can lead to the spontaneous formation of a dynamical quantum liquid crystalline phase with a rotating magnetization.

    • Iliya Esin
    • , Gaurav Kumar Gupta
    •  & Netanel H. Lindner
  • Article
    | Open Access

    Quantized response has so far eluded classical system beyond linear response theory. Here, the authors predict that a quantized classical response, arising from fundamental mathematical properties of the Green’s function, shows up in steady-state response of a non-Hermitian system without invoking a linear response theory.

    • Linhu Li
    • , Sen Mu
    •  & Jiangbin Gong
  • Article
    | Open Access

    Multistep nucleation phenomena are of considerable fundamental interest. Here the authors combine molecular dynamics, machine learning and molecular cluster analysis to investigate the multistep nucleation of smectic clusters from a nematic fluid that cannot be accounted for by the classical nucleation theory.

    • Kazuaki Z. Takahashi
    • , Takeshi Aoyagi
    •  & Jun-ichi Fukuda
  • Article
    | Open Access

    Mn3Sn is an anti-ferromagnetic material which displays a large magneto-optical Kerr effect, despite lacking a ferromagnetic moment. Here, the authors show that likewise, Mn3Sn, also presents a particularly large magneto-optical Voigt signal, with a negligible change in the quench time over a wide temperature range.

    • H. C. Zhao
    • , H. Xia
    •  & H. B. Zhao
  • Article
    | Open Access

    Free carriers and electrical polarization coexist in ferroelectric metals. Here, the authors use a capacitive method to probe the electronic compressibility of free carriers in a tunable semimetal, extract the polarized contribution, and study the carrier dependence of the ferroelectric state.

    • Sergio C. de la Barrera
    • , Qingrui Cao
    •  & Benjamin M. Hunt
  • Article
    | Open Access

    It was predicted that in the regime of strong electron-phonon interactions, electrons and phonons can form a coupled non-equilibrium state, characterized by the conservation of the total momentum and by hydrodynamic transport. Here, the authors report experimental evidence for such a coupled electron-phonon liquid in NbGe2.

    • Hung-Yu Yang
    • , Xiaohan Yao
    •  & Fazel Tafti
  • Article
    | Open Access

    Triplons are elementary spin excitations characteristic of dimerized magnets, carrying a spin angular momentum one. Here, the authors report evidence for spin current of triplons via thermal transport measurements in a spin-dimer compound CuGeO3.

    • Yao Chen
    • , Masahiro Sato
    •  & Eiji Saitoh
  • Article
    | Open Access

    In FeRh, it is possible to optically drive a phase transition between ferromagnetic (FM) and anti-ferromagnetic (AFM) ordering. Here, using a combination of photoelectron spectroscopy and ab-initio calculations, the authors demonstrate the existence of a transient intermediate phase, explaining the delayed appearance of the FM phase.

    • Federico Pressacco
    • , Davide Sangalli
    •  & Fausto Sirotti
  • Article
    | Open Access

    Skyrmions are a type of topological spin texture that great potential across a wide variety of technological applications. Here, Yu et al. study the thermally driven motion of Skyrmions and find a minimum temperature gradient for the motion of skyrmions two orders of magnitude smaller than for domain walls.

    • Xiuzhen Yu
    • , Fumitaka Kagawa
    •  & Yoshinori Tokura
  • Article
    | Open Access

    The discovery of high temperature superconductivity in hydrogen-rich compounds stimulates further extensive studies. Here, the authors report superconductivity in pressurized yttrium-hydrogen system with highest predicted Tc among binary compounds.

    • Panpan Kong
    • , Vasily S. Minkov
    •  & Mikhail I. Eremets
  • Article
    | Open Access

    The nonlinear Hall effect is a quantum phenomenon, in which two perpendicular currents induce a Hall voltage; however, previous theories for this effect has remained at the semi classical level. Here, the authors develop a full quantum theory of the nonlinear Hall effect by using the diagrammatic technique.

    • Z. Z. Du
    • , C. M. Wang
    •  & X. C. Xie
  • Article
    | Open Access

    Surface plasmons have unique physical properties that make them also interesting for technology. Here, the authors observe plasmons in mixed-dimensional heterostructures that can be highly modulated with electrostatic gating, which may be explained by plasmon hybridization

    • Sheng Wang
    • , SeokJae Yoo
    •  & Feng Wang
  • Article
    | Open Access

    Unrestricted integration of single-crystal oxide films on Si substrates allows for exploitation of emerging functionality of new materials in mature silicon devices. Here the authors integrate epitaxial oxide films with sharp metal-insulator transition on Si substrates by epitaxial lift-off of a freestanding nanomembrane.

    • Dong Kyu Lee
    • , Yunkyu Park
    •  & Junwoo Son
  • Article
    | Open Access

    Synthetic anti-ferromagnets, where two ferromagnetic layers are coupled anti-ferromagnetically via a spacer, are known for their very large current-induced domain wall velocities. Here, Guan et al show that the velocity of the domain walls in synthetic anti-ferromagnetic nanowires can be tuned over a wide range due to reversible oxidization via ionic liquid gating.

    • Yicheng Guan
    • , Xilin Zhou
    •  & Stuart S. P. Parkin
  • Article
    | Open Access

    Two-dimensional hybrid perovskites exhibiting Rashba/Dresselhaus spin-splitting can be potentially used for spin-selective transport and spin-orbitronics, yet the structural determinants of spin-splitting are not well-understood. Here, the authors reveal a specific inorganic layer distortion that correlates with bulk spin-splitting in these materials.

    • Manoj K. Jana
    • , Ruyi Song
    •  & David B. Mitzi
  • Article
    | Open Access

    Tailoring the crystallization kinetics of materials is important for targeting applications. Here the authors observe a remarkable dependence of crystallization and vitrification kinetics and attribute it to systematic bonding changes for a class of materials between metallic and covalent bonding.

    • Christoph Persch
    • , Maximilian J. Müller
    •  & Matthias Wuttig
  • Article
    | Open Access

    Fabricating materials with simultaneously spontaneous magnetic and electrical polarisations is challenging due to contradictory electronic features. Here, the authors report a synthesis path toward a perovskite MnSrTa2O7 by performing low-temperature cation-exchange reactions on Li2SrTa2O7.

    • Tong Zhu
    • , Fabio Orlandi
    •  & Michael A. Hayward
  • Article
    | Open Access

    Advanced fabrication techniques enable a wide range of quantum devices, such as the realization of a topological qubit. Here, the authors introduce an on-chip fabrication technique based on shadow walls to implement topological qubits in an InSb nanowire without fabrication steps such as lithography and etching.

    • Sebastian Heedt
    • , Marina Quintero-Pérez
    •  & Leo P. Kouwenhoven
  • Article
    | Open Access

    Widely existing self-organised complex structures in nature exhibit a high level of sophistication, yet can one program the self-assembly process to achieve similar result in the lab remains unanswered. Here, Serafin et al. present a non-Euclidean self-assembly theory for polyhedral nanoparticles that offers insight on how to manipulate the process for realising new material capabilities.

    • Francesco Serafin
    • , Jun Lu
    •  & Xiaoming Mao
  • Article
    | Open Access

    The orientation of polymer chains in the corona of polymer-grafted nanoparticles has never been measured. Here, the authors use polarized resonant soft X-ray scattering to measure local chain orientation in polystyrene grafted gold nanoparticles and quantify the thickness of the anisotropic region of the corona as well as the extent of chain orientation within it.

    • Subhrangsu Mukherjee
    • , Jason K. Streit
    •  & Dean M. DeLongchamp
  • Article
    | Open Access

    Whether the electronic nematicity is related to electronic pairing in strongly hole-doped iron-based superconductors remains controversial. Here, the authors perform transport measurements on AFe2As2 (A = K, Rb, Cs) superconductors under elastic strain, and find no indication of a nematic ordered state.

    • P. Wiecki
    • , M. Frachet
    •  & A. E. Böhmer