Reviews & Analysis

Low-temperature experiments on spin ice indicate that entropy plateaus at a value close to that estimated for water ice — a result at odds with the third law of thermodynamics. New measurements below 500 mK are consistent with the idea that spin ice finds a way to lose this residual entropy.

A reworking of the theory of particle interactions — the same theory but rendered in a new form based on twistor geometry — is likely to have wide implications for physics, including the reformulation of gravity.

Granular materials, ranging from fruit to rocks to powders, can change rapidly from a static jammed state to a free-flowing state. Insight from dynamical systems theory reveals that this tendency is governed by the growth of instabilities, rather than stress on individual particles.

In electron spin resonance techniques, spins are usually manipulated by applying external magnetic fields, but the same effect can be obtained by guiding electrons along a meandering path using surface acoustic waves.

The ability to manipulate the spin orientation of the highly spin-polarized photoelectrons ejected from topologically protected surface electrons by light polarization may pave the way for opto-spintronics applications using topological insulators.

Linking two smoke rings or tying a single ring into a knot is no easy feat. Such topological vortices are now created in water with the aid of specially printed hydrofoils.

A quantum phase transition from an antiferromagnetic to a ferromagnetic state suggests that bilayer graphene can exhibit properties analogous to those seen in topological insulators.

Recently developed experimental and theoretical tools uncover the complex and unexpected behaviour of impurities propagating through an ensemble of ultracold atoms.

Introducing connections between two distinct networks can tip the balance of power — at times enhancing the weaker system. The properties of the nodes that are linked together often determine which network claims the competitive advantage.

Observations made by the Cassini spacecraft at the bow shock of Saturn suggest that electrons are likely to be accelerated to near-relativistic energies by strong astrophysical shocks.

A snapshot of electrons crossing a metal/organic interface provides a better understanding of spin filtering and hints at new directions for designing spintronic devices.

Ionizing radiation can diffract molecules and demonstrate a novel matter-wave interferometer. Ionization gratings may now enable quantum interference with heavier particles and interferometric measurements with higher precision.

Networks as complex as national power grids must be stable enough to maintain synchrony in order to function. Understanding how this stability is achieved forms the focus of a new study that holds promise for improving grid performance.

Nitrogen atoms trapped tens of nanometres apart in diamond can now be linked by quantum entanglement. This ability to produce and control entanglement in solid systems could enable powerful quantum computers.