We report the formation and observation of an electron liquid in Sr2-xLaxTiO4, the quasi-two-dimensional counterpart of SrTiO3, through reactive molecular-beam epitaxy and in situ angle-resolved photoemission spectroscopy. The lowest lying states are found to be comprised of Ti 3dxy orbitals, analogous to the LaAlO3/SrTiO3 interface and exhibit unusually broad features characterized by quantized energy levels and a reduced Luttinger volume.

We study the crossover scaling behavior of the height-height correlation function in interface depinning in random media. We analyze experimental data from a fracture experiment and simulate an elastic line model with nonlinear couplings and disorder. Both exhibit a crossover between two different universality classes. For the experiment, we fit a functional form to the universal crossover scaling function. For the model, we vary the system size and the strength of the nonlinear term and describe the crossover between the two universality classes with a multiparameter scaling function.

We present a theory for the large suppression of the superfluid density ρs in BaFe2(As1-xPx)2 in the vicinity of a putative spin-density wave quantum critical point at a P doping, x=xc. We argue that the transition becomes weakly first order in the vicinity of xc, and disorder induces puddles of superconducting and antiferromagnetic regions at short length scales; thus, the system becomes an electronic microemulsion. We propose that frustrated Josephson couplings between the superconducting grains suppress ρs.

While the wing kinematics of many flapping insects have been well characterized, understanding the underlying sensory, neural, and physiological mechanisms that determine these kinematics is still a challenge. Two main difficulties in understanding the physiological mechanisms arise from the complexity of the interaction between a flapping wing and its own unsteady flow, as well as the intricate mechanics of the insect wing hinge, which is among the most complicated joints in the animal kingdom. These difficulties call for the application of reduced-order approaches.

To determine the thermal noise limit of graphene biotransistors, we have measured the complex impedance between the basal plane of single-layer graphene and an aqueous electrolyte. The impedance is dominated by an imaginary component but has a finite real component. Invoking the fluctuation-dissipation theorem, we determine the power spectral density of thermally driven voltage fluctuations at the graphene/electrolyte interface. The fluctuations have 1/fp dependence, with p = 0.75-0.85, and the magnitude of fluctuations scales inversely with area.

We couple magnetic tweezer techniques with standard lithography methods to make magnetically actuated single-walled carbon nanotube (SWNT) devices. Parallel arrays of 4-10 m-long SWNT cantilevers are patterned with one end anchored to the substrate and the other end attached to a micron-scale iron magnetic tag that is free to move in solution. Thermal fluctuations of this tag provide a direct measurement of the spring constant of the SWNT cantilevers, yielding values of 10-7-10-8 N/m.

Recent theoretical insights into the possibility of non-Abelian phases in ν=2/3 fractional quantum Hall states revived the interest in the numerical phase diagram of the problem. We investigate the effect of various kinds of two-body interlayer couplings on the (330) bilayer state and exactly solve the Hamiltonian for up to 14 electrons on sphere and torus geometries. We consider interlayer tunneling, short-ranged repulsive/attractive pseudopotential interactions, and Coulomb repulsion.

We demonstrate optomechanically induced amplification of carbon nanotube (CNT) mechanical modes using optical microcavities. We also show direct imaging of the spatial profile of CNT mechanical modes using optical readout. © 2015 OSA.

For centuries, practitioners of origami ( ori, fold; kami, paper) and kirigami ( kiru, cut) have fashioned sheets of paper into beautiful and complex three-dimensional structures. Both techniques are scalable, and scientists and engineers are adapting them to different two-dimensional starting materials to create structures from the macro- to the microscale1,2. Here we show that graphene3-6 is well suited for kirigami, allowing us to build robust microscale structures with tunable mechanical properties.

We use angle-resolved photoemission spectroscopy to study the doping evolution of infinite-layer Sr1-xLaxCuO2 thin films grown by molecular-beam epitaxy. At low doping, the material exhibits a dispersive lower Hubbard band typical of the superconducting cuprate parent compounds. As carriers are added to the system, a continuous evolution from charge-transfer insulator to superconductor is observed, with the initial lower Hubbard band pinned well below the Fermi level and the development of a coherent low-energy band with electron doping.