Seven decades after the discovery of collective spin excitations in microwave-irradiated ferromagnets, there has been a rebirth of magnonics. However, magnetic nanodevices will enable smart ...GHz-to-THz devices at low power consumption only, if such spin waves (magnons) are generated and manipulated on the sub-100 nm scale. Here we show how magnons with a wavelength of a few 10 nm are exploited by combining the functionality of insulating yttrium iron garnet and nanodisks from different ferromagnets. We demonstrate magnonic devices at wavelengths of 88 nm written/read by conventional coplanar waveguides. Our microwave-to-magnon transducers are reconfigurable and thereby provide additional functionalities. The results pave the way for a multi-functional GHz technology with unprecedented miniaturization exploiting nanoscale wavelengths that are otherwise relevant for soft X-rays. Nanomagnonics integrated with broadband microwave circuitry offer applications that are wide ranging, from nanoscale microwave components to nonlinear data processing, image reconstruction and wave-based logic.
Wave control in the solid state has opened new avenues in modern information technology. Surface-acoustic-wave-based devices are found as mass market products in 100 millions of cellular phones. Spin ...waves (magnons) would offer a boost in today's data handling and security implementations, i.e., image processing and speech recognition. However, nanomagnonic devices realized so far suffer from the relatively short damping length in the metallic ferromagnets amounting to a few 10 micrometers typically. Here we demonstrate that nm-thick YIG films overcome the damping chasm. Using a conventional coplanar waveguide we excite a large series of short-wavelength spin waves (SWs). From the data we estimate a macroscopic of damping length of about 600 micrometers. The intrinsic damping parameter suggests even a record value about 1 mm allowing for magnonics-based nanotechnology with ultra-low damping. In addition, SWs at large wave vector are found to exhibit the non-reciprocal properties relevant for new concepts in nanoscale SW-based logics. We expect our results to provide the basis for coherent data processing with SWs at GHz rates and in large arrays of cellular magnetic arrays, thereby boosting the envisioned image processing and speech recognition.
We present R times GOC, 10-37 mu m spectra of 53 ultraluminous infrared galaxies (ULIRGs), taken using the infrared Spectrograph on board Spitzer. The spectra show fine-structure emission lines of ...neon, oxygen, sulfur, silicon, argon, chlorine, iron, and phosphorous; molecular hydrogen lines, and C sub(2)H sub(2), HCN, and OH super(-) absorption features. We employ diagnostics based on the fine-structure lines, the polycyclic aromatic hydrocarbon (PAH) features and the 9.7 mu m silicate absorption feature, to show that the infrared emission from most ULIRGs is powered mostly by star formation, with only similar to 20% of ULIRGs hosting an AGN with a greater IR luminosity than the starburst. The detection of Ne v lambda 14.32 in just under half the sample, however, implies that an AGN contributes significantly to the mid-IR flux in similar to 42% of ULIRGs. The starbursts and AGNs in ULIRGs appear more extincted, and for the starbursts more compact than those in lower luminosity systems. The excitations and electron densities in the narrow-line regions of ULIRGs appear comparable to those of starbursts with L unk10 super(11.5) L unk, although the NLR gas in ULIRGs may be more dense. We show that the Ne II A12.81 + Ne III lambda 15.56 luminosity correlates with both infrared luminosity and the luminosity of the 6.2 and 11.2 urn PAH features, and derive a calibration between PAH luminosity and star formation rate. Finally, we show that ULIRGs with silicate absorption strengths S sub(sil) of 0.8 unk S sub(sil) unk 2.4 are likely to be powered mainly by star formation, but that ULIRGs with S sub(sil) unk 0.8, and possibly those with S sub(sil) unk 2.4, contain an IR-luminous AGN.
Aspergillus section Nigri comprises filamentous fungi relevant to biomedicine, bioenergy, health, and biotechnology. To learn more about what genetically sets these species apart, as well as about ...potential applications in biotechnology and biomedicine, we sequenced 23 genomes de novo, forming a full genome compendium for the section (26 species), as well as 6 Aspergillus niger isolates. This allowed us to quantify both inter- and intraspecies genomic variation. We further predicted 17,903 carbohydrate-active enzymes and 2,717 secondary metabolite gene clusters, which we condensed into 455 distinct families corresponding to compound classes, 49% of which are only found in single species. We performed metabolomics and genetic engineering to correlate genotypes to phenotypes, as demonstrated for the metabolite aurasperone, and by heterologous transfer of citrate production to Aspergillus nidulans. Experimental and computational analyses showed that both secondary metabolism and regulation are key factors that are significant in the delineation of Aspergillus species.
We present spectra taken with the Infrared Spectrograph on Spitzer covering the 5-38 km region of the 10 ultraluminous infrared galaxies (ULIRGs) found in the IRAS Bright Galaxy Sample (BGS). There ...is a factor of 50 spread in the rest-frame 5.5-60 km spectral slopes, and the 9.7 km silicate optical depths range from at least t sub(9.7) , 0.4 (A sub(V) 6 8) to t sub(9.7) . 4.2 (A sub(V) . 78). There is evidence for water ice and hydrocarbon absorption and C sub(2)H sub(2) and HCN absorption features in 4 and possibly 6 of the 10 BGS ULIRGs, indicating shielded molecular clouds and a warm, dense ISM. We have detected Ne V emission in 3 of the 10 BGS ULIRGs, at flux levels of 5-18 x 10 super(-14) ergs cm super(-2) s super(-1) and Ne super(V) 14.3/Ne super(II) 12.8 line flux ratios of 0.12-0.85. The remaining BGS ULIRGs have limits on their Ne super(V)/Ne super(II) line flux ratios, which range from ,0.15 to ,0.01. Among the BGS ULIRGs, the AGN fractions implied by either the Ne super(V) /Ne super(II) or O super(IV)/Ne super(II) line flux ratios (or their upper limits) are significantly lower than implied by the MIR slope or strength of the 6.2 km PAH EQW feature. There is evidence for hot (T> 300 K) dust in five of the BGS ULIRGs, with the fraction of hot dust to total dust luminosity ranging from 61% to 23%, before correcting for extinction. When integrated over the IRAC-8, IRS blue peak-up, and MIPS-24 filter bandpasses, the IRS spectra imply very blue colors for some ULIRGs at z 6 1.3. The large range in diagnostic parameters among the nearest ULIRGs suggests that matching survey results to a small number of templates may lead to biased results about the fraction of luminous dusty starbursts and AGNs at high z.
We present a Spitzer-based mid-infrared (MIR) study of a large sample of blue compact dwarfs (BCDs) using the Infrared Spectrograph (IRS), including the first MIR spectrum of I Zw 18, the archetype ...for the BCD class and among the most metal-poor galaxies known. We show the spectra of polycyclic aromatic hydrocarbon (PAH) emission in a low-metallicity environment. We find that the equivalent widths (EWs) of PAHs at 6.2, 7.7, 8.6, and 11.2 km are generally weaker in BCDs than in typical starburst galaxies and that the fine-structure line ratio, Ne III/Ne II, has a weak anticorrelation with the PAH EW. A much stronger anticorrelation is shown between the PAH EW and the product of the Ne III/Ne II ratio and the UV luminosity density divided by the metallicity. We conclude that the PAH EW in metal-poor high-excitation environments is determined by a combination of PAH formation and destruction effects.
We present 5-38 km mid-infrared spectra at a spectral resolution of R - 65-130 of a large sample of 22 starburst nuclei taken with the Infrared Spectrograph (IRS) on board the Spitzer Space ...Telescope. The spectra show a vast range of starburst SEDs. The silicate absorption ranges from essentially no absorption to heavily obscured systems with an optical depth of t sub(9.8) k sub(m) 6 5. The spectral slopes can be used to discriminate between starburst and AGN powered sources. The monochromatic continuum fluxes at 15 and 30 km enable a remarkably accurate estimate of the total infrared luminosity of the starburst. We find that the PAH equivalent width is independent of the total starburst luminosity L sub(IR) as both continuum and PAH feature scale proportionally. However, the luminosity of the 6.2 km feature scales with L sub(IR) and can be used to approximate the total infrared luminosity of the starburst. Although our starburst sample covers about a factor of 10 difference in the Ne III/Ne II ratio, we found no systematic correlation between the radiation field hardness and the PAH equivalent width or the 7.7 km/11.3 km PAH ratio. These results are based on spatially integrated diagnostics over an entire starburst region, and local variations may be "averaged out." It is presumably due to this effect that unresolved starburst nuclei with significantly different global properties appear spectrally as rather similar members of one class of objects.
We present an atlas of Spitzer/IRS high-resolution (R ~ 600) 10-37 Delta *mm spectra for 24 well known starburst galaxies. The spectra are dominated by fine-structure lines, molecular hydrogen lines, ...and emission bands of polycyclic aromatic hydrocarbons (PAHs). Six out of the eight objects with a known active galactic nucleus (AGN) component show emission of the high excitation Ne V line. This line is also seen in one other object (NGC 4194) with, a priori, no known AGN component. In addition to strong PAH emission features in this wavelength range (11.3, 12.7, 16.4 Delta *mm), the spectra reveal other weak hydrocarbon features at 10.6, 13.5, 14.2 Delta *mm, and a previously unreported emission feature at 10.75 Delta *mm. An unidentified absorption feature at 13.7 Delta *mm is detected in many of the starbursts. We use the fine-structure lines to derive the abundance of neon and sulfur for 14 objects where the H I 7-6 line is detected. We further use the molecular hydrogen lines to sample the properties of the warm molecular gas. Several basic diagrams characterizing the properties of the sample are also shown. We have combined the spectra of all the pure starburst objects to create a high signal-to-noise ratio template, which is available to the community.
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