Search

Cooperative paramagnetism refers to a strongly correlated state without long range magnetic order that occurs in frustrated magnetic systems between the Neel temperature and Curie-Weiss temperature. Here, using resonant elastic magnetic and inelastic x-ray scattering, Terilli et al find a spectrally sharp gapped magnetic excitations that persists above the Neel temperature in Y₂Ir₂O₇, implying a cooperative paramagnetic phase.

The surface properties of topological insulators are protected by time-reversal symmetry. Now, the finding of a topological crystalline insulator with metallic boundary states protected by lattice symmetries promises novel functionality.

3D higher-order topological insulators (HOTIs) exhibit 1D hinge states depending on extrinsic sample details, while intrinsic features of HOTIs remain unknown. Here, K.S. Lin et al. introduce the framework of spin-resolved topology to show that helical HOTIs can realize a doubled axion insulator phase with nontrivial partial axion angles.

The photoinduced hidden metallic state in 1T-TaS₂ has so far been stabilized only at cryogenic temperatures. Now it is shown that accessing an additional mixed-phase long-lived metastable state can stabilize the hidden phase at higher temperatures.

Antiferromagnets have a variety of attractive features for spintronic devices; they are inherently robust against external magnetic fields, and have fast, terahertz, dynamics. However, terahertz magnons are usually strongly damped. Here, Choe, Lujan and coauthors find that the zone boundary magnons in the AFM insulator CoTiO3 exhibit long lifetimes.

Electrical readout of the state of an antiferromagnet is an important goal for spintronic applications. Now, detection of the electrical voltage created by a thermal gradient in a canted antiferromagnet suggests a route for achieving this goal.

The proximity effect enables the injection of Cooper pairs from a superconductor into a normal metal, but they usually do not travel far into the metal. A study of the propagation of Cooper pairs from irregularly shaped superconducting islands on a metal film finds that they can travel further than expected for certain island geometries.

A major advance in the quantum theory of solids allows materials to be identified whose electronic states have a non-trivial topology. Such materials could have many computing and electronics applications. See Article p.298

MnBi2Te4, referred to as MBT, is a van der Waals material combining topological electron bands with magnetic order. Here, Lujan et al study collective spin excitations in MBT, and show that magnetic fluctuations increase as samples reduce in thickness, implying less robust magnetic order.

Scanning tunnelling microscopy provides evidence for topological superconductivity in a naturally occurring transition metal dichalcogenide material.

The behaviour of strongly correlated nickelates is well studied in bulk but the corresponding strained thin films are largely unexplored. Here, the authors study strained NdNiO₃thin films with various degrees of strain and, in addition to a metal-to-insulator transition, find quantum critical behaviour.

Topological insulators are often considered to be one-band problems that are easy to solve. However, strongly correlated topological insulators cannot be described by band theory because the electrons fractionalize into other degrees of freedom.

Spectroscopic study of the low-energy excitations in magnetite Fe₃O₄ shows the signatures of its charge-ordered structure involved in the metal–insulator transition, whose building blocks are the three-site small polarons, termed trimerons.