Articles in 2022

The investigation of microswimmer dynamics provides key insights in the design of active microfluidic systems and opens doors for further studies on inertial active matter. The authors establish a theoretical foundation for the dynamics of microswimmers in confined microflows with finite fluid inertia and demonstrate non-trivial impact of inertia in a microchannel flow.

The advent of petawatt lasers has reignited interest in the generation of positrons, since they could provide enough energy for practical applications. Here, an all-optical method for the generation of short, energetic positron beams are described numerically.

Exquisite control of loss and gain in non-Hermitian systems allows waves to propagate in unusual and useful ways. Here, unidirectional amplification is achieved in an acoustic metamaterial by dynamically varying the gain and loss with modulation phase delay between different metaatoms.

Judicious design of acoustic metamaterials has so far permitted control of topologically-protected waves in one plane of a two-dimensional system. Here, the symmetry of a phononic crystal is tuned geometrically to realise independent tuning of both in-plane and out-of-plane topological modes in the same frequency range.

Laser pulses can be used not only to investigate the ultrafast dynamics of a magnetic system but also to manipulate their magnetization states with potential applications in information storage. To this end, using time-dependent electronic structure simulations, the authors investigate the underlying physics of the laser-induced ultrafast magnetization dynamics in bulk nickel and predict magnetization reversal with a single pulse.

Intense research efforts have provided mechanistic insight into the spin and anomalous Hall effects in metallic samples, but the effect of extrinsic defects is not yet understood. Here, a scaling law describing the spin Hall response of PtO films with increasing oxygen levels reveals an analogy with the anomalous Hall effect in the insulating regime.

The origin of the pseudogap in the cuprates and how it is related to the mechanism of their superconductivity has been a topic of long standing debate. Here, the authors suggest that the pseudogap is governed by a unified energy law the basis for which lies in the theory of wall turbulence.

The emergence of self-organization is a widely investigated property of living matter. Here the authors aim at bridging living and non-living complex self-organizing systems by showing that some types of life-like dynamics and functionalities can emerge in elementary dissipative quantum systems driven out of equilibrium.

Superradiant phase transitions, predicted to occur in the ultra-strong light-matter coupling regime, may offer a route to robust quantum coherence but have not yet been observed at thermal equilibrium. Here, such a transition is predicted in ErFeO₃ at about 4 K, revealing unique ground state properties.

Modulation instability refers to the sensitivity of dispersive, weakly nonlinear systems to small perturbations and may be used as a source of optical gain. Here, the phase-sensitive properties of modulation instability with harmonic seeding in passive fiber resonators are investigated in theory and experiments.

Heterostructures comprising of different materials provide the possibility to engineer devices with specific properties based on the individual characteristics and interactions between the different components. Here, the authors report the detection of proximity-induced spin-triplet Cooper pairs in a superconductor/ferromagnet/superconductor Josephson junction made of NbN and GdN respectively.

The strong nonlinearity and absence of particle conservation leads to non-equilibrium nature of exciton-polariton condensates. Here, an unsupervised machine learning approach is employed to map phases of a polariton condensate lattice, and classify unique polarization patterns

Fermi-liquid theory has been used to successfully describe the behaviour of metals for decades but there are a number of instances where expected behaviour is violated, such as for high-temperature superconductors. Here, the authors identify parameters which could be responsible for the strange metal behaviour and establish how this affects resistivity and specific heat measurements.

The mechanisms underlying clogging of granular materials exiting a container have been widely studied, but findings have been sometimes contradictory for other systems or active matter in general. The authors experimentally analyze the effect of an obstacle to prevent silo clogging, finding that the obstacle has a dual role altering both the kinematic properties of the system and the distribution of contact orientations

Relaxor ferroelectrics are a type of material exhibiting electrostriction whereby a change in the material shape occurs under an applied electric field; however, although known by the community for many years the underlying mechanisms of the phenomenon and the characteristic relaxations still remain under debate. To help address this issue, the authors report an equivalent circuit analysis revealing the key role of a constant phase element in the behaviour of relaxor ferroelectric single crystals.

Coherent perfect absorption allows control of light, with wide ranging applications. Here, this concept is experimentally implemented in the presence of non-linearities, where the formation of a self-induced exceptional point coherent perfect absorption mechanism is identified.

While methods for estimating the entropy production rate of a stationary process are relatively well established, this is still a challenge in non-stationary conditions. Here, the authors propose a scheme to infer the exact value of the time-dependent entropy production rate as well as entropy production along with single realizations directly from trajectory data.