Volume 11 Issue 6, June 2015

Coupling electromagnetic waves to mechanical waves has led to a remarkable miniaturization of wireless communication technologies. Now, spin waves could provide us with technologies that are small and reprogrammable.

Spin–orbit entangled local moments in the iridate material Na₂IrO₃ are subject to strong exchange frustration, driving the system towards a spin-liquid phase with emergent fractional excitations.

New observations suggest that two highly debated mechanisms for type Ia supernovae — our standard distance 'candles' for astrophysical objects — may both be correct.

Condensation usually describes a winner-takes-all phenomenon, in which a single state is macroscopically occupied. Game theory now reveals a mechanism for selecting an entire network of condensate states in a driven quantum system.

Forming molecules from atoms is commonplace in dense atomic gases. But it now seems that some two-dimensional materials provide a suitable environment for creating complex molecular states from the hydrogen-like electron–hole pairs that form in semiconductors.

Three papers published in Nature Physics in 2009 revealed the intriguing three- and four-body bound states arising from the predictions by Vitaly Efimov nearly half a century ago. But some of these findings continue to puzzle the few-body physics community.

Magnons provide a route for information-processing technologies that are free from charge-related dissipations. Advances in the manipulation of magnons, and the conversion to charge currents, bring magnon-based computing closer to realization.

Honeycomb iridates have been proposed as experimental realizations of the Kitaev model. An X-ray scattering study presents evidence for bond-directional interactions in Na₂IrO₃, a key requirement to make the connection with Kitaev physics possible.

Understanding low-temperature molecular collisions is challenging, but using non-resonant photodetachment makes it possible to study the state-resolved dynamics of the inelastic collisions between hydroxyl ions and cold helium buffer gas.

The effect of electron–phonon interactions on transport properties of 2D materials is unclear. Transport measurements on atomically thin Nb₃SiTe₆ crystals now show that reduced dimensionality results in the suppression of electron–phonon coupling.

Strong many-body Coulomb interactions allow for bound two- and three-body excitonic states to form in monolayer transition metal dichalcogenides, but it is now shown that such interactions are strong enough to create four-body biexcitonic states.

Monoclinic transition metal dichalcogenides offer the possibility of topological quantum devices, but they are difficult to realize. One route may be through switching from the common hexagonal phase, for which a method is now shown.

The periodic modulation of the magnetic properties of magnonic crystals controls the flow of spin waves. An optical method is now shown that can produce such modulations by heating, which can be reprogrammed during operation.

Simulations help reveal the complex relationship between the changing structure of the magnetic field lines and the plasma in the corona of the Sun, which is one hundred times hotter than the surface itself.

The spin Hall effect induces spin currents in nonmagnetic layers, which can control the magnetization of neighbouring ferromagnets. The transparency of the interface is shown to strongly influence the efficiency of such manipulation.

Understanding the physical mechanisms of photon–atom interactions on ultrafast timescales is challenging, but a new theoretical framework enables the interpretation of attoclock experiments measuring tunnelling times in hydrogen.

Gauge/gravity duality is normally reserved for the study of black holes, but it can be applied to the study of out-of-equilibrium quantum systems in arbitrary dimension.

The price of exploration.

Although mostly based on electron charges, information processing technologies also make use of the electron spin. This Focus surveys the field of magnon spintronics, which harnesses quantized spin waves – magnons – as the carriers of spin currents.