It has been known for more than 60 years that fine metal whiskers can spontaneously form at the surface of a stressed metal, and that these whiskers produce random failures in computer servers, satellites, and electronic storage devices. A new study attributes the whiskers to minute electric field variations at metal surfaces, leading to the first predictive theory for whisker growth and length distribution.

It has been known for more than 60 years that fine metal whiskers can spontaneously form at the surface of a stressed metal, and that these whiskers produce random failures in computer servers, satellites, and electronic storage devices. A new study attributes the whiskers to minute electric field variations at metal surfaces, leading to the first predictive theory for whisker growth and length distribution.

Resonant nanoparticles allow devices to be constructed to selectively concentrate, guide, or scatter light in unique ways—for example, to make highly efficient solar cells or transparent displays. In this work, scientists develop a method to intentionally design nanoparticles with desired characteristics. This approach provides a promising new tool, which the authors demonstrate by designing a novel nanoparticle laser.

Applications of terahertz radiation include security imaging, nondestructive testing, novel spectroscopic applications, and skin cancer diagnostics. In this work, a “stereometamaterial” constructed from geometrically placed copper rings acts as a perfect absorber and exhibits rotationally asymmetric absorption behavior. Mimicking chiral molecules found in nature, this device offers new possibilities for customized functionality at terahertz frequencies.

Spin pumping is the process of generating spin currents used in spintronic devices such as ultrahigh density storage media. In this work, significantly improved transport efficiency of spin pumping is achieved in Y${}_3$Fe${}_5$O${}_{12}$-based heterostructures. This improvement can be understood in terms of spin conductance matching and offers the potential of reduced energy consumption in spintronic applications.

Photoluminescent semiconductors are increasingly important for applications such as optoelectronic devices, near-infrared imaging sensors, and multiple-junction solar cells. The authors show that by using a patterned microarray of germanium crystals on silicon pillars, light emission efficiency can be increased by over two orders of magnitude.

The storage and transport of spin currents in spintronic devices are typically controlled by inputs of electrical current. This work instead proposes applying a voltage to excite a propagating spin wave in an ultrathin ferromagnetic heterostructure. This so-called “voltage-controlled magnetic anisotropy” technology could lead to significantly decreased power consumption and improved compatibility with conventional semiconductor devices.

Bragg mirrors can be used to direct a free-electron laser’s x-ray beam onto a sample, but the mirrors are extensively cratered by the intense beam. To create a mirrored surface that is reproducible from one laser shot to the next, the authors in this work lithograph micropillars from a single mirrored crystal of silicon, and demonstrate a strategy whereby each shot of the laser reflects light from one pillar surface, and a fresh micropillar would then be indexed into position for the next shot.