Search

Topological state in Kondo insulators has been provoked in SmB₆, but the origin of surface states and topological order remain elusive. Here, Hagiwara et al. report temperature dependent reconstruction of a metallic surface state on the (001) surface of YbB₁₂driven by Kondo effect and discuss its origin from topology.

Observing and tuning the Kondo effect in graphene is experimentally challenging. Here, the authors identify the spectroscopic signature of Kondo screening in graphene, along with a quantum phase transition between screened and unscreened phases of vacancy magnetic moments.

Previous work exploring the robustness of topological surface states to perturbations has mostly focused on surfaces with the same atomic structure as the bulk. Here the authors demonstrate the effect of surface reconstruction on the topological surfaces on the (100) surface of SmB6.

The authors observe a coherent Kondo lattice in a monolayer of VSe₂ grown on a superconducting 2H-NbSe₂ substrate. Superconductivity is established in the Kondo lattice through proximity effect from the substrate.

The Kondo effect from magnetic impurities has been proposed as a probe of fractionalized excitations in a topological quantum spin liquid. Lee et al. experimentally demonstrate the Kondo effect in a Kitaev candidate material α-RuCl3 with dilute Cr impurities.

The Kondo insulator samarium hexaboride exhibits low-temperature transport anomalies, which might be due to topological surface states. Here Jiang et al.perform angle-resolved photoemission and its circular dichroism measurements, which suggest that the anomalies might be of topological origin.

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.

Samarium hexaboride, a well-known Kondo insulator, shows transport anomalies at low temperatures, which recently have been proposed to be of topological origin. Using laser- and synchrotron-based photoemission techniques, Neupane et al. find evidence for a topological Fermi surface.

Experimental study of the Kondo insulator SmB₆ provides an alternative route to realize a Fermi surface in the absence of a conventional Fermi liquid.

Unconventional superconductivity is usually associated with a layered system. But how thin can a layered superconductor be and continue to be superconducting? Painstakingly grown superlattices of the heavy-fermion superconductor CeCoIn₅ suggest it could be as thin as a single layer.

The Kondo effect—the screening of a magnetic impurity’s local moment by the electron Fermi sea in a metal—has been observed in a charge-insulating quantum spin liquid material, where the spinon excitations take the role of electrons.

A quantum critical point occurs when different stable phases of matter are in equilibrium at absolute zero temperature. Describing quantum criticality with a theoretical framework that unifies different types of transitions is highly desirable to understand how phenomena such as superconductivity and magnetism interact in correlated electron systems. A study now provides an indication of an underlying universality of quantum criticality, and highlights the role of dimensionality in such a unified theory.

In molecular spintronics, the spin state of a molecule may be switched by changing the molecular structure. Here, the spin of a single-molecule magnet is switched by applying an electric current using a scanning tunnelling microscope, which may aid in information coding at the single-molecule level.

The strength of the interaction between the spin state and orbital motion of electrons in a semiconducting quantum dot can be controlled by electrical gates.

Anisotropic hybridization between conduction and unpaired f electrons is rarely observed. Now, a lanthanide-based two-dimensional compound exhibits nodal hybridization, giving rise to heavy-fermion behaviour.

Quantum spin liquids are a state of magnetic order that, in analogy with ordinary liquids, is characterized by fluctuating, disordered spins. By means of specific heat measurements, the frustrated Kondo system Pr₂Ir₂O₇ is shown to undergo a transition to such a state in zero magnetic field.

The authors report that the metallic spin-1/2 chain compound Ti₄MnBi₂ forms near a quantum critical point with inherent frustration. They identify strong 1D spin and 3D electron coupling that should stimulate the search for materials exhibiting a 1D Kondo effect and heavy fermions.

We present comprehensive thermodynamic and spectroscopic evidence for an antiferromagnetically ordered heavy-fermion ground state in the van der Waals metal CeSiI.

Weyl fermions are evidenced in weakly correlated electron systems, but whether they survive strong electron correlations remains obscure. Here, Guo et al. report evidence of the chiral anomaly, topological Hall effect and a cubic temperature dependence of specific heat, suggesting existence of Weyl fermions in a heavy fermion semimetal YbPtBi.

The unconventional behaviour of samarium hexaboride has been difficult to explain in part because of differences between samples. Here the authors use gadolinium to exemplify that hard to avoid impurities introduce a low energy density of states that may explain earlier observations.

Single molecules on metal surfaces are paradigmatic systems for the study of many-body phenomena. Here, the authors show that several spectroscopic experiments on iron phthalocyanine on Au(111) surface can be described in a unified way in terms of a strongly interacting topologically non-trivial (non-Landau) Fermi liquid.

Electrons in f orbitals can create localized states that interact strongly and drive strange metal and critical behaviour via the Kondo mechanism. Now a mechanism of geometric frustration enables similar phenomena with d electrons.

Samarium hexaboride has unusual electronic properties that have been suggested to arise from topological effects. Here the authors present spin-resolved ARPES measurements of the (111) surface and observe surface states that may give insight into the bulk topological properties.

Charge-neutral excitations have been proposed to explain metal-like thermal transport in Kondo insulators. Here, the authors demonstrate the coupling between charge-neutral excitations and spin degrees of freedom in a Kondo insulator YbIr₃Si₇, which puts restrictions on current theories.

Despite all of the fundamental research carried out on them, artificial atoms continue to be a source of surprise. The intersection between the electrons in a quantum dot and a nearby sea of electrons can create unusual many-body states. A spectroscopic study now makes these states observable.

The interactions of quasiparticles can be described by renormalizing their masses, such that some materials have a vanishingly small effective mass, whereas others have a very high effective mass. The observation by Vyalikh and colleagues of both extremes occurring on the surface and interior of the same material offers a new view of many-body interactions.

Manipulating spin states of molecules in a controllable manner is essential to develop the molecule-based spintronics technologies. Here, Ormaza et al. show how to use the interaction between a single metallocene molecule and a metallic surface to reversibly switch spin from 1 to ½ in a junction.

Pr₂Ir₂O₇ is a candidate for a metallic spin liquid with a quantum critical point; however, the exact nature of its ground state and quantum criticality is unknown. Here, the authors report strong deviations from dipolar spin-ice ground state and find normal electronic behavior near quantum criticality.

Pigment pattern formation in zebrafish depends on the interactions between the pigment cells. Here the authors present a mathematical model based on mutual interaction of pigment cells in the absence of cell motion, revising the current model of the pattern formation that relies on reaction–diffusion Turing patterns.

The spin Hall effect and its inverse allow conversion between charge and spin currents in both magnetic and nonmagnetic materials. Weiet al.observe an anomaly in the temperature dependence of the inverse spin Hall effect, which suggests that it can also be used as a sensor for very small magnetic moments.

In heavy fermion metals, exotic states such as superconductivity depend to a large extent on whether unpaired electrons can become delocalized from the magnetic sites. The authors demonstrate that the primary driving force behind delocalization is the local environment of the rare earth ions and the strength of the resulting charge fluctuations.

Although LaAlO₃ and SrTiO₃ are both insulators, when they are brought together at a (100) interface, a highly conducting two-dimensional electron gas forms between them. Annandi et al.show that this also happens at a (110) interface, counter to expectations that it should not.

Electrically manipulating molecular magnetism is a challenge to overcome for applications in high-density storage. Here, the authors use inelastic electron tunneling spectroscopy to show that a vibron-assisted spin excitation in a nickel-nickelocene complex exceeds a pure spin excitation in energy and amplitude.

The realization of the anomalous Hall effect in high-mobility two dimensional electron systems has so far remained elusive. Here, the authors observe its emergence in MgZnO/ZnO heterostructures and attribute it to skew scattering of electrons by localized paramagnetic centres.

Magnetically intercalated transition metal dichalcogenides provide a platform to study the interplay of magnetism, electronic band structures, and correlations. Here the authors demonstrate a nearly magnetization-free anomalous Hall effect, collinear antiferromagnetism and non-Fermi liquid behavior in V_1/3NbS₂.

Nuclear magnetic resonance measurements reveal two separate relaxation channels—one associated with a Fermi liquid state and the other with a non-Fermi liquid state—coexisting near a quantum phase transition in YbRh₂Si₂.

Achieving deep blue emission and high practical efficiency in organic light-emitting devices remains a considerable challenge. Here, the authors report late-stage double borylation of boron/nitrogen based multi-resonance frameworks, achieving maximum efficiency of over 32% in stable devices.

In most superconductors, the pairing-up of electrons responsible for resistance-less conduction is driven by vibrations of the solid's crystal lattice. But other materials exist in which the attractive interaction responsible for binding electrons is believed to have a very different origin: quantum fluctuations of spin or charge. This paper identifies an unusually 'violent' generalization of such pairing mechanisms, in which these spin and charge instabilities combine forces.

Samarium hexahoride is argued to be a topological Kondo insulator, but this claim remains under debate. Here, Hlawenka et al. provide a topologically trivial explanation for the conducting states at the (100) surface of samarium hexaboride; an explanation based on Rashba splitting and a surface shift of the Kondo resonance.

A quantum critical point associated with a carbon nanotube quantum dot that is in contact with dissipative leads exhibits striking non-Fermi-liquid properties and anomalous scaling. The dissipative environment enables the comparison of the system under thermal- and non-equilibrium conditions.

The authors study a YbCoIn5/CeCoIn5/YbRhIn5 heterostructure. Using non-reciprocity in the second harmonic transport response, they demonstrate the existence of a specific form of finite-momentum pairing called a helical superconducting state, where the phase of the order parameter is spontaneously spatially modulated.

Despite much recent effort, the highest reported T_c of the infinite-layer nickelates remains lower than 15 K. Here, the authors apply pressure to Pr_0.82Sr_0.18NiO₂ thin films and observe a monotonic increase of T_c to 31 K at 12.1 GPa, an increase that does not level off with increasing pressure.

The back-action of electrons can cool a nanomechanical oscillator to a few-quantum state when a current flows through a suspended nanotube. The electron back-action, which is attributed to an electrothermal effect, also induces self-oscillations.

In compounds containing 4f and 5f elements, hidden-order phases exist which are undetectable by many methods, the origins of which are debated. Here, the authors use photoemission and neutron scattering methods to show how such a multipolar-ordered phase emerges due to Fermi surface instability in CeB₆.