The highly localized, periodic force induced by resonant transmission of acoustic waves via a phononic crystal is capable of trapping, aligning, sorting, and transferring large numbers of particles according to size or density, all in a tunable and scalable manner. This approach exploits a flexural mode unavailable to conventional optical techniques, using an engineered acoustic field to raise power transmission from the 10% predicted by classical theory to 60%. This advance has implications for cell sorting, additive materials fabrication, and targeted drug delivery.

The highly localized, periodic force induced by resonant transmission of acoustic waves via a phononic crystal is capable of trapping, aligning, sorting, and transferring large numbers of particles according to size or density, all in a tunable and scalable manner. This approach exploits a flexural mode unavailable to conventional optical techniques, using an engineered acoustic field to raise power transmission from the 10% predicted by classical theory to 60%. This advance has implications for cell sorting, additive materials fabrication, and targeted drug delivery.

A crucial challenge of condensed-matter physics today is to engineer, at a microscopic level, the properties of functional materials for electronic device applications. This work shows that in strontium titanate, a transparent insulator widely used in oxide heterostructures, it is possible to tailor metallic states with different symmetries on the different bare surfaces of a single material, with no need to fabricate heterostructures or complex interfaces. This work opens the way for new, two-dimensional exotic states in correlated-electron materials.

Quantum dots can provide electronic states that act as “stepping stones” in absorbing light, thereby improving the efficiency of solar cells. The authors identify a transition temperature at which a significant gain in solar energy absorption is seen in GaSb/GaAs quantum dots, and show that this gain is due to a particular alignment of bands in the underlying electronic structure. Related behaviors could also be valuable in optoelectronics and quantum information processing.

It is well known that the torque from a spin-polarized current can be used to switch the magnetization of memory elements. This study shows that mechanical vibrations can also be used to either assist or inhibit switching through spin-transfer torque. This finding implies that the minimal current needed to switch magnetic memory elements can potentially be reduced, and by identifying vibrational parameters that provoke or impede magnetic flipping, the authors provide direction for the potential design of future nanoscale devices.

Silicene nanoribbons are quasi-one-dimensional layered honeycomb lattices, analogous to graphene but composed of silicon. Researchers here present first-principles calculations for silicene nanoribbon structures folded out of plane in a zig-zag. These calculations show that although these systems are similar to graphene nanoribbons, they also feature enhanced spin-orbit interaction effects, a width-dependent antiferromagnetic to ferromagnetic transition, and other characteristics of potential importance to spintronics applications.

Modern angle-resolved photoemission spectroscopy (ARPES) measures the electronic structure of a sample with parallel detection of energy and momentum. Spin resolution, increasingly important for the study of nonmagnetic samples such as topological insulators, is, however, still restricted to single-channel mode. The authors show the feasibility of oxygen-passivated iron as a polarizing electron mirror in future spin-resolving display-type analyzers.

The “gas tank” of a hydrogen-powered vehicle is typically made of aluminum, which unfortunately could become brittle and fail under long term exposure to its contents—a serious safety concern. In this paper, researchers introduce a reliable and computationally efficient potential energy function for the study of aluminum and aluminum hydrides. This should permit computations at sufficiently large scales to analyze embrittlement and other problems important to the engineering of hydrogen storage technologies for advanced vehicles.

Ongoing advances in semiconductor fabrication are expected to enable nonlinear optical circuits to operate at extremely low switching energies, where quantum effects become important. This work describes semiclassical simulations to study the effects of quantum noise in large digital logic circuits containing hundreds of optical components. The authors find that the amplitudes of quantum fluctuations do not increase as signals propagate through the circuit, which is promising for scaling up devices.

Manganite-based perovskite oxides have long been known to exhibit technologically important interactions between magnetic and electrical properties, and these properties become even more remarkable when the materials are prepared as epitaxial thin films. This study reveals that the magnetism in thin films of Eu${}_{0.7}$Sr${}_{0.3}$MnO${}_3$ depend strongly on epitaxial strain, varying from para- to ferromagnetic, while electrically the films remain insulating. This unusual combination of tunable magnetism and robust insulating behavior could facilitate novel applications such as piezoelectrically controlled spin injection.