Articles in 2015

Negative refraction can produce optical Veselago lenses with a resolution that is not diffraction-limited. Similar lenses can also be made for electrons, with negative refraction of Dirac fermions now shown in graphene.

Career opportunities are often a matter of chance, but also of a willingness to cross interdisciplinary boundaries.

In 2009, two papers provided the first unambiguous examples of three-dimensional topological insulators — bulk insulators boasting metallic surface states with massless Dirac electrons. These now form just one of many classes of topological materials.

A nonlinear Compton scattering experiment with X-ray photons using an X-ray free-electron laser exhibits an unexpected frequency shift — hinting at the breakdown of standard approximations.

Boxed in.

After two Nobel prizes, the quest to uncover new physics continues at the Kamioka site in Japan.

The internal structure of cells is organized into compartments, many of which lack a confining membrane and instead resemble viscous liquid droplets. Evidence is mounting that these compartments form via spontaneous phase transitions.

The rotational motion of liquids can induce a flow of electron spins, and could enable ultra-small spin-hydrodynamic generators that operate with liquid metals.

What happens to correlated electronic phases—superconductivity and charge density wave ordering—as a material is thinned? Experiments show that both can remain intact in just a single layer of niobium diselenide.

Magnetohydrodynamic generators use magnetic fields to convert the kinetic energy of conducting fluids into electricity. Fluid motion is now shown to generate spin currents, which can induce electric voltages without applying magnetic fields.

Electric-field-induced superconductivity in samples of ultrathin FeSe grown on SrTiO₃ and MgO substrates shows that the superconductivity is not an interfacial effect but is rather related to a charge imbalance of electrons and holes.

Certain bacteria swim by rotating a single helical filament, moving forwards and backwards with similar speeds. The discovery that the torque is not equal in both directions links them to multifilament species with opposite filament handedness.

Determining—and defining—the size of an atomic nucleus is far from easy. First-principles calculations now provide accurate information on the neutron distribution of the neutron-rich ⁴⁸Ca nucleus—and constraints on the size of a neutron star.

The Mott insulator Sr₂IrO₄ is intensively studied because of its electronic similarity to the high-temperature cuprate superconductor La₂CuO₄. Now, spectroscopic experiments reveal evidence for a hidden order with odd-parity symmetry in this system.

Hydrostatic pressure is used as a means to tune the two-dimensional electron gas hosted in a GaAs/AlGaAs crystal from a topologically ordered to a spontaneously broken symmetry phase.