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Tuning the structure in the atomic scale enables manipulation of the quantum state in a molecular based system. Here, Hiraokaet al. tune the Kondo coupling between molecular spins and the Au electrode by controlling the position of Fe²⁺ions in the molecular cage with a tip.

The Kondo effect usually refers to increased electrical resistance in metals due to spin-spin interactions between localized magnetic impurities and conduction electrons. Here the authors report a Kondo-like coupling between a light-induced exciton and localized impurity spins in Nd-doped hybrid perovskite.

Semiconducting graphene nanoribbon provides a platform for band-gap engineering desired for electronic and optoelectronic applications. Here, Li et al. show that graphene nanoribbon can effectively mediate the interaction of molecular magnetic moment and electronic spin in underlying metallic substrates.

In rare-earth intermetallics, interaction between localized 4f electrons and itinerant electrons can result in exotic states of matter. Here, the authors use photoemission spectroscopy to reveal and study this interaction in the bulk and at the surface of the Kondo lattice antiferromagnet CeRh₂Si₂.

Sensitive measurements of fluctuations in the current through carbon-nanotube-based quantum dots provide insight into the many-body physics of such systems.

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.

Understanding the physics of transition metal oxides that move beyond the commonly studied 3d orbital state is important for future studies. Taking the (CaCu₃)B₄O₁₂ family as an example, Meyers et al.examine the electronic and magnetic structure as the B-site changes from Co to Rh and Ir.

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.

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.

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.

In a quantum dot in the Kondo regime, electrical charges are effectively frozen, but the quantum dot remains electrically conducting owing to strong electron–electron correlations.

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.

A single iron atom adsorbed on a platinum surface can act as the basic constituent of a Hund's metal—known as a Hund's impurity—and its magnetic properties can be probed and manipulated using the tip of a scanning tunnelling microscope.

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.

A longstanding mystery in condensed-matter physics involves the appearance of a 'hidden order' state in URu₂Si₂ at low temperature — an unexpected phase change that is accompanied by a sharp change in the bulk properties of the material. The problem is related to the appearance of a 'heavy fermion' state. Here, scanning tunnelling microscopy and spectroscopy have been used to image the electronic structure of URu₂Si₂ at sub-atomic resolution, revealing how the hidden order state evolves with decreasing temperature.

A tunable concentration of localized magnetic impurities is inserted into a metal from a molecular monolayer, which allows many-body phenomena in magnetic impurity–host systems to be studied at unprecedented impurity concentrations.

Under chemical pressure, two phase transitions that were seemingly linked become detached in YbRh₂Si₂, thereby clarifying a long-standing mystery in the heavy-electron metals. Moreover, a new quantum phase appears under negative pressure.

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.

Skyrmions are a type of topological spin texture, which can exist as both an isolated state, and as a skyrmion crystal. Here, Hayami et al present a theoretical study of phase shifts in skyrmion crystals, showing how such phase shifts can lead to other crystalline topological spin textures.

Information technology based on few atom magnets requires both long spin-energy relaxation times and flexible inter-bit coupling. Here, the authors show routes to manipulate information in three-atom clusters strongly coupled to substrate electrons by exploiting Dzyaloshinskii–Moriya interactions.

The nature of quantum criticality in intermetallic f-electron compounds exhibiting valence fluctuations is not well understood. Here, using a combination of experimental techniques, the authors attribute quantum criticality in YbAlB₄ to the anisotropic hybridization between the conduction and f-electrons.

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.

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 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.

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.

Multiple quantum critical behaviors exist in the heavy fermion material CeRhIn5, but their interrelation is less studied. Here, Helm et al. investigate the interrelation of two quantum critical points and other relevant orders, revealing a strongly non-mean-field-like phase diagram.

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.

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.

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.

The coupling of spin and orbital motion of electrons in carbon nanotubes has been demonstrated before, but a study now shows that the strength and sign of the spin–orbit coupling can be tuned by a gate voltage, and that, importantly for future applications, the effect survives in the presence of disorder.

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.

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.

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 pairing gap of the high-T_c cuprates has been expected to close at the transition temperature, similarly to the case of conventional superconductors. Here the authors perform ARPES measurements on Bi2212, and reveal a point nodal gap formation beyond T_c, characterized in terms of three parameters.

The superconductor UTe₂ exhibits a reentrant superconducting phase at magnetic fields above 40 T for particular field angles. Here, from high-field Hall-effect measurements, T. Helm et al. find evidence for a partial compensation between the applied field and an exchange field, pointing to the Jaccarino-Peter effect as a possible mechanism for the reentrant superconductivity.

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.

The insulator-to-metal transition in vanadium dioxide still has many unexplored properties. Here the authors use multi-modal THz and mid-IR nano-imaging to examine the phase transition in VO₂ thin films, and discuss the unexpectedly smooth transition at THz frequencies in the context of a dimer Hubbard model.