Large Anomalous Hall effect in a silicon-based magnetic semiconductor

Magnetic semiconductors are attracting high interest because of their potential use for spintronics, a new technology which merges electronics and manipulation of conduction electron spins. (GaMn)As and (GaMn)N have recently emerged as the most popular materials for this new technology. While Curie temperatures are rising towards room temperature, these materials can only be fabricated in thin film form, are heavily defective, and are not obviously compatible with Si. We show here that it is productive to consider transition metal monosilicides as potential alternatives. In particular, we report the discovery that the bulk metallic magnets derived from doping the narrow gap insulator FeSi with Co share the very high anomalous Hall conductance of (GaMn)As, while displaying Curie temperatures as high as 53 K. Our work opens up a new arena for spintronics, involving a bulk material based only on transition metals and Si, and which we have proven to display a variety of large magnetic field effects on easily measured electrical properties.Comment: 19 pages with 5 figure

Multiheterodyne spectroscopy using interband cascade lasers

© 2017 The Authors. While midinfrared radiation can be used to identify and quantify numerous chemical species, contemporary broadband midinfrared spectroscopic systems are often hindered by large footprints, moving parts, and high power consumption. In this work, we demonstrate multiheterodyne spectroscopy (MHS) using interband cascade lasers, which combines broadband spectral coverage with high spectral resolution and energy-efficient operation. The lasers generate up to 30 mW of continuous-wave optical power while consuming <0.5W of electrical power. A computational phase and timing correction algorithm is used to obtain kHz linewidths of the multiheterodyne beat notes and up to 30 dB improvement in signal-to-noise ratio. The versatility of the multiheterodyne technique is demonstrated by performing both rapidly swept absorption and dispersion spectroscopic assessments of low-pressure ethylene (C2H4) acquired by extracting a single beat note from the multiheterodyne signal, as well as broadband MHS of methane (CH4) acquired with all available beat notes with microsecond temporal resolution and an instantaneous optical bandwidth of ∼240GHz. The technology shows excellent potential for portable and high-resolution solid-state spectroscopic chemical sensors operating in the midinfrared

Analysis of the major loss processes in mid-infrared type-II "W" diode lasers

The results from high-pressure and low-temperature measurements on mid-infrared type-II W-structure lasers suggest that Auger recombination is the major loss process that prevents their continuous-wave operation at room temperature.</p

Temperature sensitivity of mid-infrared type II "W" interband cascade lasers (ICL) emitting at 4.1μm at room temperature

The thermal properties of 5-stage “W” Interband-Cascade Lasers emitting at 4.1μm at RT are investigated. It is shown that inter-valence band absorption coupled with non-radiative recombination govern their maximum operating temperature

Multi-species detection using mid-infrared multi-mode absorption spectroscopy, MUMAS

Multi-mode absorption spectroscopy has been used to detect CH4, NH3 and N2O individually or simultaneously in mixtures using multi-mode radiation generated by difference frequency generation at 3.3 μm or inter-band cascade lasers at 3.7 μm. © 2014 OSA