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Heavy-fermion materials have unusual electronic behavior due to a dual localized-itinerant character of 4f electrons. Here, by studying divalent EuRh₂Si₂, the authors gain insight into the electronic states of the trivalent heavy fermion system YbRh₂Si₂ and show that it experimentally demonstrates Luttinger’s theorem.

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.

Open-shell nanographenes are used to fabricate length-controlled antiferromagnetic spin-1/2 Heisenberg chains. It is revealed that the spin excitation spectra evolve from gapped to gapless following a power-law dependence on chain length, along with the visualization of the standing waves of confined single spinons.

The identification of the magnetic-fluctuation mode at a quantum phase transition of the archetypical heavy-fermion compound Ce_1−xLa_xRu₂Si₂ indicates that quantum criticality in this system is governed by collective antiferromagnetic behaviour, rather than by local magnetic moments as has been suggested.

Coupling superconductors to mesoscopic systems leads to unusual effects that could be exploited in new devices including topological quantum computers. Here the authors present a double quantum dot with a Yu–Shiba–Rusinov ground state arising from the interplay of Coulomb interactions and superconductivity.

Building on ideas from quantum information science and on recent experimental advances, the use of ultracold alkaline-earth atoms in optical lattices as quantum simulators of many-body phenomena is proposed. The corresponding models possess a high degree of symmetry and may provide fundamental insights into strongly correlated systems.

The anomalous Hall effect is a macroscopic manifestation of a quantum mechanical effect. Here, Uelandet al. report the observation of a high Hall conductivity in the heavy-fermion compound UCu5, a metallic system, and explain its origin in terms of geometric frustration effects.

Recent work has expanded the concept of altermagnets to non-collinear magnetic materials. Here, Hu et al extend this further to non-collinear chiral materials, determining altermagnetic multipolar order parameters and predicting that such materials host large spin-hall and Edelstein effects.

Large spin-orbit coupling in solids has the potential to yield materials that can display unique properties such as non-trivial topological ordering. Steele et al.report an order of magnitude higher zero-field spin splitting in carbon than has been measured previously.

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 insertion of a few unit-cell-thick EuTiO₃ layers at the interface between LaAlO₃ and SrTiO₃ leads to the formation of an electric-field-tunable quasi-two-dimensional electron system where ferromagnetism and superconductivity coexist.

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.

Topological frustration in the π-electron network of the polycyclic aromatic hydrocarbon C₃₈H₁₈ yields unpaired electrons and a magnetically non-trivial ground state. Here, the authors synthesize this molecule, known as Clar’s goblet, on Au(111) and characterize the antiferromagnetic ground state with scanning tunnelling microscopy.

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.

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.

Theoretical work has highlighted the potential of using devices in which spin-polarized carries are injected in single molecular magnets, and a few experiments have shown promising results. The challenges are great, but the advantages compared with more conventional strategies may be considerable, and future research promises to be intriguing and rewarding.

LaNiO₃ is a strange metal, for reasons that are not well understood. Here, Liu et al. report evidence for scattering of charge carriers by antiferromagnetic quantum fluctuations in high-purity epitaxial thin films of LaNiO₃, suggesting it is close to an antiferromagnetic quantum critical point.

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.

Magnetic atomic chains assembled on the surface of superconductors are a potential platform for engineering topological superconducting phases. Here the authors step towards this by manipulating magnetic atoms at interstitial sites to tune interatomic interactions and control the Yu-Shiba-Rusinov states that form.

The formation of Ising quasiparticles in URu₂Si₂ results from ‘hastatic’ order, which breaks double time-reversal symmetry, mixing states of integer and half-integer spin, and accounts for the large entropy of condensation and the magnetic anomaly observed in torque magnetometry.

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.

Recently, it has been shown that Co1/3TaS2 hosts a four-sublattice ‘3Q state’, which has a sizable scalar spin chirality and thus a large anomalous Hall effect. Here, Kim et al demonstrate electrical control of this 3Q state via ionic gating.

Nanographenes, as their name suggests, are small sections of graphene. They offer a diverse array of magnetic behaviors; for example, sublattice imbalances in the nanographene lead to unpaired spins. Here, Du et al uncover a large variation in the exchange energy in nanographenes, due to changes in the frontier orbital symmetries.

Symmetry is key for magnetism of molecules as well as other nanostructures. Here, the authors tune the magnetic moment of a metal-organic molecule deposited on NbSe2 via the adsorption symmetry, and observe a non-collinear intramolecular spin-spin interaction.

Recently, rich condensed matter physics has emerged from the interplay between band topology and magnetic order. Here, the authors characterize the magnetic Weyl semimetal CeAlGe and find evidence for the role of Weyl fermions in stabilizing the magnetic order above the local transition temperature.

A proposed theoretical explanation for the electronic behaviour of moiré graphene is the coexistence of light and heavy electrons. Now local thermoelectric measurements hint that this model could be accurate.

Broadband optical spectroscopy is used to obtain optical spectra of RCd₃P₃ (R: Ce or La), which exhibit a Fermi-liquid behavior with a very low charge carrier density. Notably, our first-principles calculations suggest that subtle displacements of Cd1 and P1 atoms within the unit cell can induce a semiconductor-to-metal transition, emphasizing the sensitivity of electronic structures to atomic positioning. The temperature-dependent anomalies of infrared-active phonons suggest a structural phase transition in these compounds. Our findings will offer a fundamental understanding of structural distortions leading to electronic transitions, which may be relevant for broader applications in correlated electron systems.

Metallic systems in magnetic fields enter the quantum limit when the cyclotron energy exceeds the Fermi energy. Here the authors introduce the analogue of the quantum limit for insulators, where the Zeeman energy exceeds the cyclotron energy, and show that it explains key features of the Kondo insulator YbB₁₂.

A phase battery is a quantum device that provides a persistent phase bias to the wave function of a quantum circuit. A hybrid superconducting and magnetic circuit containing two anomalous Josephson junctions can provide a tunable Josephson phase that persists in the absence of external stimuli.

Nickelates have recently joined the cuprates and iron pnictides as unconventional superconductors with transition temperatures above 80 K. This Review looks for their shared superconducting mechanisms for building a coherent theoretical framework.

Understanding metal-molecule contacts is crucial for molecular electronic devices. Here, the authors use a C60-terminated scanning tunnelling tip to probe how the chemical nature of the contacting atom on the substrate electrode determines the transport properties.

Previous studies of magnetic adatom chains on superconducting substrates have mostly focused on the regime of dense chains and classical spins. Here, using scanning tunnelling microscopy, the authors study the excitation spectra of Fe chains on a NbSe₂ surface, adatom by adatom, in the regime of quantum spins.

Freezing of gait (FOG) is among the most debilitating symptoms of Parkinson disease. This Consensus Statement from the International Consortium for Freezing of Gait presents new guidelines for the definition and assessment of FOG, with the aim of harmonizing the study and management of the condition.

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.

The heavy fermion compound URu₂Si₂displays a hidden order phase and superconductivity at low temperatures. Here, the authors perform substitution studies—partially replacing silicon with phosphorus—and study the effects on hidden order and superconductivity.

Thermoelectric performances depend on phonon and electron transport. Here, Takahashi et al. show that the large Seebeck coefficient observed in high-purity single-crystal FeSb₂ is due to the phonon-drag effect and to the high effective mass of delectrons interacting with quasi-ballistic phonons.

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.

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.

Understanding the strange metal behavior, characterized by linear-in-temperature resistivity, could shed light on the mechanism of unconventional superconductivity. Here, by using electrical resistivity measurements into the micro-Kelvin regime, the authors report evidence of unconventional superconductivity in the strange metal YbRh₂Si₂ and propose a possible pairing mechanism.