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The Ruderman–Kittel–Kasuya–Yosida interaction indirectly couples the moments of magnetic atoms through conduction electrons. Using a spin-polarized scanning tunnelling microscope, the direction and strength of this interaction between pairs and triplets of isolated atoms on a surface has been imaged directly.

The Shastry-Sutherland model consists of orthogonal dimers in a two dimensional plane, and has proved a rich basis for both theoretical and experimental investigation of quantum magnetism. Here, Brassington et al show that Yb2Be2SiO7 hosts an anisotropic variant of the Shastry Sutherland model.

Examples of materials with non-trivial band topology in the presence of strong electron correlations are rare. Now it is shown that quantum fluctuations near a quantum phase transition can promote topological phases in a heavy-fermion compound.

The authors study (Bi,Sb)₂Te₃/FeTe bilayers, which feature emergent superconductivity at the interface with T_c ~ 12 K. Through angle-resolved photoemission spectroscopy and electrical transport measurements, they argue that the Dirac-fermion-mediated Ruderman-Kittel-Kasuya-Yosida-type interaction weakens antiferromagnetic order in FeTe layer, allowing for superconductivity.

Magnetic skyrmions typically form hexagonal crystals with either uniquely Bloch or Néel-type textures. Here, a polar magnet EuNiGe₃ is shown to host two skyrmion crystal phases with hexagonal and square structures, and hybrid Bloch-Néel textures.

Kondo materials exhibit extremely rich physics, from unconventional superconductivity to topological phases. Unfortunately, for a real material, direct solution of the Kondo lattice is practically impossible. Here, Simeth et al. present a tractable approach to this problem, showing how a multi-orbital periodic Anderson model can be reduced to a Kondo lattice model, and be applied to relevant materials and quantitatively validated with neutron spectroscopy.

Topological magnetic spin structures such as skyrmions and merons have the potential to be used in magnetic information devices. Now multistep transformations between such structures are demonstrated in a centrosymmetric material.

Interface effects in complex oxides could have interesting technological applications. Ariandoet al. demonstrate electronic phase separation and rich physics at a complex oxide interface between the two non-magnetic insulators LaAlO₃ and SrTiO₃.

Incoherent transport is an important feature of many anisotropic quantum materials but often its origin is not well understood. Here, the authors show that in a layered quantum magnet, incoherence is driven by the interaction of electrons with spin fluctuations after the melting of magnetic order.

Spin textures, such as skyrmions, could be useful in future low-power-consumption memory devices, but they are usually only seen in materials with a strong spin-orbit interaction. Phark et al.now, however, observe such non-collinear magnetic order in nanometre-scale bilayer iron islands.

The spin helicity in helimagnets may be exploited in magnetic memory applications if electrically controllable and detectable. Here, helicity manipulation driven by an electric current and detection by second harmonic resistivity measurements in an itinerant helimagnet MnP is demonstrated.

Functional behaviour can emerge in materials in which magnetic order is determined by the interplay of localised and itinerant magnetic interactions. Here the authors tune such magnetic order in a photovoltaic perovskite by tuning the electronic carrier concentration under visible light illumination.

The heavy fermion system CeRhIn₅has a local quantum critical point, but its role in the onset of superconductivity is unclear. Here, the authors tune the quantum critical point by tin doping and verify that fluctuations from the antiferromagnetic criticality promote this unconventional superconductivity.

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.

It may be possible to find non-Abelian electronic states in the higher bands of flat-band materials. Now a detailed transport study of the second moiré band of twisted bilayer MoTe₂ maps out several topological and magnetic states.

Metallic van der Waals magnets have considerable technological promise, due to their ability to be strongly coupled with electronic currents and integrated in two dimensional heterostructures. Here, Seo et al. demonstrate highly tunable itinerant antiferromagnetism in a van der Waals magnet.

Extending magnetic nanostructures into three dimensions offers a vast increase in potential functionalities, but this typically comes at the expense of ease of fabrication and measurement. Here, Dion et al. demonstrate an approach to creating three dimensional magnetic nanostructures while retaining easy fabrication and readout of established two dimensional approaches.

FeGe is a Kagome metal that exhibits a very rich array of magnetic and electronic phases. Here, using neutron scattering, Chen et al add to this zoo, by showing the emergence of a spin density wave order.

Transport measurements of the metallic kagome spin ice HoAgGe show that it has an emergent discrete symmetry that is not apparent from measurements of its magnetization.

The Weyl fermions in NdAlSi mediate a helical incommensurate spin density wave, providing a rare example of Weyl-mediated collective phenomena.

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.

A Weyl semimetal formally requires either broken time reversal symmetry or inversion symmetry. One class of Weyl semimetals-the crystal family of NdAlSi-exhibits both. Here, Li et al perform angle-resolved photoemission spectroscopy measurements on NdAlSi, and observe the formation of an additional Weyl fermion as the material becomes ferrimagnetic.

Manipulating topological spin textures are demanded for future spintronic devices, but knowledge about phase transitions among different spin textures remain limited. Here, Fujishiro and Kanazawa et al. report chemical-pressure-controlled phase transitions between different topological spin textures in chiral magnets MnSi_1−xGe_x.

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.

Inα-GeTe, ferroelectric polarization acts to break inversion symmetry of the lattice and induce a strong Rashba-type spin splitting of the electronic band structure. Here, the authors study how this effect competes with Zeeman splitting due to ferromagnetic exchange coupling in Mn-doped GeTe.

Theoretically predicted fractional antiferromagnetic skyrmions are experimentally realized in MnSc₂S₄ and are found to originate from anisotropic couplings over nearest neighbours in the crystal lattice.

Spin liquids and spin ices arise when spins arranged on a lattice have several states that are close in energy, a phenomenon referred to as frustration. Here, Klich et al.show that quantum fluctuations can induce a spin liquid to freeze into a glassy state.

Doping a topological insulator with magnetic impurities is expected to induce ferromagnetism and open a band gap in its surface states. Here, the authors study Mn-doped Bi₂Se₃, finding a mechanism for band gap opening in topologically-protected surface states which is not of magnetic origin.

Small-angle neutron scattering experiments of the layered antiferromagnet Ca₃Ru₂O₇ reveal a metamagnetic spin texture that is indicative of an extraordinary coexistence of spin orders belonging to different symmetries.

A multipole polaron, composed of a mobile electron dressed with a cloud of the quadrupole crystal-electric-field polarization, is identified in a rare-earth intermetallic.

Arranging magnetic impurities in a conventional superconductor may give rise to Majorana bound states and their manipulation. Here, the authors report focusing and long-range extension of magnetic bound states from magnetic impurities embedded below a superconducting La(0001) surface.

Antiferromagnetic spintronics may pave the way to innovative information storage devices with perpendicular coupling, however experimental demonstrations are still sparse. Here, the authors demonstrate a graphene-mediated perpendicular antiferromagnetic coupling between Fe and Co layers in a Fe/graphene/Co sandwich structure.

Cryo-electron microscopy structures of the voltage-gated potassium channel Kv4.2 alone and in complex with auxiliary subunits (DPP6S and/or KChIP1) reveal the distinct mechanisms of these two different subunits in modulating channel activity.

The superconductivity is found to control the magnetic configuration in GdN/Nb/GdN spin valves as a result of an antiferromagnetic exchange interaction arising from the coupling between the superconducting condensation energy and the magnetic state.

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.

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.

Using terahertz pulses, the quasiparticle dynamics of the heavy-fermion compound CeCu_6−xAu are investigated in the vicinity of its quantum critical point.

The effect of spin orbit interactions on a typical BCS superconductor is becoming an important area of research for phenomena such as Majorana fermions and topological superconductivity. The authors investigate the effect of Pb clusters on the spin susceptibility of superconducting Al films via spin orbit interactions.

The heavy-fermion compound YbRh₂Si₂ possesses a quantum critical point, at which the standard theory of electron behaviour in metals is expected to break down; such anomalous behaviour has now been observed.