Volume 9 Issue 10, October 2013

Rapid cooling across a phase transition leaves behind defects; from domain walls in magnets to cosmic strings. The Kibble–Zurek mechanism that describes this formation of defects is seen at work in the spontaneous creation of solitons in an atomic Bose–Einstein condensate.

For almost a century, deviations of Ohm's law have been known to occur in electrolyte solutions. Now, lattice model simulations of these systems are providing valuable insight into the microscopic mechanisms involved.

The current understanding of the relaxation dynamics in quantum many-body systems is still incomplete, but an ultracold atom experiment brings new insights by confirming the local emergence and propagation of thermal correlations.

Although electrically charged black holes seem remote from superconductors and strange metals in the laboratory, they might be intimately related by the holographic dualities discovered in string theory.

The metallic sheet at the heterointerface between two different insulating and non-magnetic oxides displays seemingly conflicting ferromagnetic properties that may be explained by the presence of a spiral magnetic structure.

On cooling, transition metal oxides often undergo a phase change from an electrically conducting to an insulating state. Now it is shown that the metal–insulator transition temperature of vanadium dioxide thin films can be controlled by applying strain.

Cold atoms trapped in dissipative optical lattices can behave in ways that cannot be described within the framework of Boltzmann–Gibbs statistical mechanics. Recent theoretical and experimental developments may lead to a better understanding of these processes.

By growing a topological insulator on top of a high-temperature superconducting substrate it is possible to induce superconductivity in the surface states of the topological insulator. Moreover, the pairing symmetry of the induced superconductivity is s-wave, unlike the d-wave symmetry of the substrate.

The interface between two non-magnetic band insulators, LaAlO₃ and SrTiO₃, can exhibit conductivity, superconductivity and magnetism. These interfacial phenomena can be reconciled by a theory that predicts a spiral magnetic ground state.

Ensembles of nuclear spins display thermal fluctuations—spin noise—that interfere with nuclear magnetic resonance measurements of samples below a threshold size. Experiments on nanowires show that by monitoring spin noise in real time and applying instantaneously adjusted radiofrequency pulses, spin polarization distributions that are narrower than the thermal distribution can be obtained.

Measurements of the spin heat accumulation at the ferromagnetic/non-magnetic interface in nanopillar spin valves show that spin-up and spin-down electrons have different temperatures. This observation is important for the design of magnetic thermal switches and the study of inelastic spin scattering.

The relaxation mechanisms of isolated quantum many-body systems are insufficiently understood, but a one-dimensional quantum gas experiment uncovers the local emergence of thermal correlations and their cone-like propagation through the system.

The fluctuation relations are a central concept in thermodynamics at the microscopic scale. These relations are experimentally verified by measuring the entropy production in a single-electron box coupled to two heat baths.

Strongly interacting condensed-matter systems are often computationally intractable. By introducing a periodic lattice to a holographic model developed by string theorists, it becomes possible to study anisotropic materials that are insulating in certain directions but conducting in others.

The Kibble–Zurek mechanism describes the spontaneous formation of defects in systems that are undergoing a second-order phase transition at a finite rate. Familiar to cosmologists and condensed matter physicists, this mechanism is now found to be responsible for the spontaneous creation of solitons in a Bose–Einstein condensate.

Bulk vanadium dioxide undergoes a metal–insulator transition near room temperature. It is now shown that by putting a thin layer of vanadium dioxide on a buffer, and varying the buffer’s thickness, the orbital occupancy in the metallic state and the transition temperature can be tuned.

Networks of networks are vulnerable: a failure in one sub-network can bring the rest crashing down. Previous simulations have suggested that randomly positioned networks might offer some limited robustness under certain circumstances. Analysis now shows, however, that real-world interdependent networks, where nodes are positioned according to geographical constraints, might not be so resilient.

Models for the topology or dynamics of various networks abound, but until now, there has been no single universal framework for complex networks that can separate factors contributing to the topology and dynamics of networks across biological and social systems.