Organic semiconductors that are pi-conjugated are emerging as an important platform for 'spintronics', which purports to harness the spin degree of freedom of a charge carrier to store, process and/or communicate information. Here, we report the study of an organic nanowire spin valve device, 50 nm in diameter, consisting of a trilayer of ferromagnetic cobalt, an organic, Alq3, and ferromagnetic nickel. The measured spin relaxation time in the organic is found to be exceptionally long-between a few milliseconds and a second-and it is relatively temperature independent up to 100 K. Our experimental observations strongly suggest that the primary spin relaxation mechanism in the organic is the Elliott-Yafet mode, in which the spin relaxes whenever a carrier scatters and its velocity changes.

Abstract. We describe two electrochemical self-assembly processes for producing highly ordered quasi-periodic arrays of quantum dots on a surface. The advantages of these techniques are: (i) they are 'gentle' and do not cause radiation damage to nanostructures unlike beam lithography, (ii) they have high throughput and are amenable to mass production unlike direct-write lithography, (iii) structures can be delineated on non-planar substrates, and (iv) the techniques are potentially orders of magnitude cheaper to implement than conventional nanosynthesis. Samples produced by these techniques have been characterized by microscopy, optical and transport measurements, Auger and x-ray. These measurements reveal intriguing properties of the nanostructures. In this paper, we describe our initial results and show the promise of such techniques for low-cost and high-yield nanosynthesis.

We report a Raman spectroscopy investigation of electrochemically self-assembled quasiperiodic arrays of CdS quantum dots with characteristic feature size of 10 nm. The dots were synthesized using electrochemical deposition of CdS into a porous anodized alumina film. Polarization-dependent Raman scattering study over an extended frequency range reveals the quantization of electronic states in the conduction band and intersubband transitions. Raman peaks observed at 2919 and 3050 cm Ϫ1 are attributed to transitions between the lowest two subbands. The results suggest that quantum dot arrays, produced by inexpensive robust electrochemical means, may be suitable for infrared detector applications.

Programmable photonic circuits of reconfigurable interferometers can be used to implement arbitrary operations on optical modes, providing a flexible platform for accelerating tasks in quantum simulation, signal processing, and artificial intelligence. A major obstacle to scaling up these systems is static fabrication error, where small component errors within each device accrue to produce significant errors within the circuit computation. Mitigating this error usually requires numerical optimization dependent on real-time feedback from the circuit, which can greatly limit the scalability of the hardware. Here we present a deterministic approach to correcting circuit errors by locally correcting hardware errors within individual optical gates. We apply our approach to simulations of large scale optical neural networks and infinite impulse response filters implemented in programmable photonics, finding that they remain resilient to component error well beyond modern day process tolerances. Our results highlight a potential way to scale up programmable photonics to hundreds of modes with current fabrication processes.

In the present Rapid Communication, we explore superconductivity in NdNiO 2 and LaNiO 2 employing a first-principles derived low-energy model Hamiltonian, consisting of two orbitals: Ni x 2 -y 2 , and an axial orbital. The axial orbital is constructed out of Nd/La d, Ni 3z 2 -r 2 , and Ni s characters. Calculation of the superconducting pairing symmetry and pairing eigenvalue of the spin-fluctuation mediated pairing interaction underlines the crucial role of the interorbital Hubbard interaction in superconductivity, which turns out to be orbital selective. The axial orbital brings in material dependence to the problem, making NdNiO 2 different from LaNiO 2 , thereby controlling the interorbital Hubbard interaction-assisted superconductivity.