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Results for “Ferromagnetic resonance”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Absence of detectable spin and orbital pumping from Ni to Nb by out-of-plane ferromagnetic resonance

Excited ferromagnets can pump spin angular momentum, along with possibly orbital angular momentum. Among elemental ferromagnets, Ni has been proposed to exhibit substantial orbital pumping relative to spin pumping. Here, in this study, we search for a signature of orbital pumping by Ni, specifically by comparing out-of-plane ferromagnetic resonance in heterostructures without Ni (FeV/Nb) and with Ni (FeV-Ni/Nb). The FeV/Nb series shows a clear increase in Gilbert damping with the Nb sink thickness, attributed to spin pumping from FeV to Nb. Surprisingly, the FeV-Ni/Nb series exhibits no such damping increase, revealing no significant spin or orbital pumping from Ni to Nb. Our results offer a fresh perspective on angular-momentum transfer in Ni/Nb heterostructures.

Bakare, Omolara A [Virginia Polytechnic Inst. and ↗
DOE OSTI2022

Local Ferromagnetic Resonance Measurements of Mesoscopically Patterned Ferromagnets Using Deterministically Placed Nanodiamonds

Nitrogen-vacancy centers in diamond have recently been established as effective sensors of the magnetization dynamics in vicinal ferromagnetic materials. Here, we demonstrate sub-100-nm placement accuracy of nitrogen-vacancy-containing nanodiamonds and use these as local sensors that probe optically detected ferromagnetic resonance in mesoscopically patterned Permalloy islands. These measurements reveal variations in the ferromagnetic resonance signal at different sites on these structures with distinct behavior in the edge and the bulk of patterned features. These test measurements establish an easily implemented approach for spatially targeted measurements of spin dynamics in mesoscale ferromagnets. In principle, the methodology can also be extended to local studies of nanoscale ferromagnets, such as single magnetic nanowires and nanoparticles.

30 DIRECT ENERGY CONVERSION↗
NASA NTRS1974

Ferromagnetic resonance studies of thermal effects on lunar metallic Fe phases

Ferromagnetic resonance results of annealing experiments are discussed which illustrate the thermal effects on lunar metallic iron phases already present in a lunar fines sample. Spectral features of ferromagnetic resonance produced in the sample by heat treatments at temperatures between 600 and 1025 C are described which resemble those detected in lunar breccias and crystalline rocks. A correlation is shown to exist between these features and the degree of thermal metamorphism. It is noted that this correlation can be used as a built-in geothermometer or probe to investigate the thermal history and degree of metamorphism of a lunar sample containing metallic iron phases. The thermal history of a metaclastic rock is analyzed in this way, and it is shown that thermal metamorphism is an effective process for increasing relaxation times or the stability of the natural remanent magnetization carried by single-domain metallic iron particles.

Tsay, F.-D.↗
NASA NTRS1982

Ferromagnetic resonance intensity - A rapid method for determining lunar glass bead origin

Ferromagnetic resonance intensity, I(s), relies on the absence or presence of single-domain Fe formed during impact melting by autoreduction of Fe(2+) in the melt to distinguish volcanic from impact glass spherules in the lunar soil. SEM inspection of individual glass bead surfaces gave reliable evidence of the mode of glass genesis. Ferromagnetic resonance intensity was tested against the Apollo 15 and 17 volcanics. I(s) values of less than one were found in 94% of the volcanic glasses, implying the absence of single-domain Fe, while 75% of the impact glasses had elevated I(s) values. These samples lack single-domain Fe, and may represent impact melts of bedrock with little or no regolith contribution. Both the primary discrimination of volcanic and impact glasses, and the secondary one of bedrock-derived impact melts from impact melts partially or entirely derived from regolith, have been demonstrated for the I(s) technique.

Stone, C. D.↗
NASA NTRS1979

Effect of sample quantity on the results of ferromagnetic resonance studies of lunar samples

Quantitative ferromagnetic resonance (FMR) measurements at 9.5 and 35 GHz were made on lunar fines in order to determine the amount of single domain FE(0) and to ascertain the effect of sample quantity on the results of these experiments. Samples containing more than 10 micrograms of Fe(0) in an X-band TE(104) cavity, or more than 0.11 micrograms in a Ka-band cavity can cause errors greater than 1% in the quantitative determination of Fe(0), as well as cause anomalous broadening of the FMR line. Theoretical calculations were derived to show this effect which results from a nonlinear response of the FMR experiment with the sample quantity. Using samples of nominal weights, the amount of Fe(0) determined at 34 GHz was 1.1-1.8 times greater than at 9.5 GHz, while the linewidths increased by a factor of 1.2. As the particle size increases, the ratio of Fe(0) determined at 35 GHz to that determined at 9.5 GHz increases, suggesting that the additional iron is due to larger spheroidal particles which change from multidomain to single domain at the larger fields.

Goldberg, J. B.↗
DOE OSTI2023

Ferromagnetic resonators synthesized by metal-organic decomposition epitaxy

Abstract Metal-organic decomposition epitaxy is an economical wet-chemical approach suitable to synthesize high-quality low-spin-damping films for resonator and oscillator applications. This work reports the temperature dependence of ferromagnetic resonances and associated structural and magnetic quantities of yttrium iron garnet nanofilms that coincide with single-crystal values. Despite imperfections originating from wet-chemical deposition and spin coating, the quality factor for out-of-plane and in-plane resonances approaches 600 and 1000, respectively, at room temperature and 40 GHz. These values increase with temperature and are 100 times larger than those offered by commercial devices based on complementary metal-oxide semiconductor voltage-controlled oscillators at comparable production costs.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS1976

Petrographic and ferromagnetic resonance studies of the Apollo 15 deep drill core

Detailed petrographic grain size, and ferromagnetic resonance studies were performed on a representative suite of samples from the Apollo 15 deep drill core. Petrographic analyses of the 90-150 micron size fraction show a subtle upward increase in the ratio of mare to highland components. The agglutinate content at the FMR intensity normalized to FeO show that the soils in the core are generally immature to submature. The most striking feature shown by the maturity indices is a systematic decrease in maturity from the lunar surface to a depth of about 40 cm. Although other mechanisms are possible, the downward decrease in maturity can be attributed to in situ reworking over a time span of 400 m.y. at a 50% probability.

Heiken, G. H.↗
NASA NTRS1976

Ferromagnetic resonance and magnetic studies of cores 60009/60010 and 60003 - Compositional and surface-exposure stratigraphy

Ferromagnetic resonance and static magnetic measurements were made on 131 samples from core 60009/60010 and on 40 samples from section 60003 of the Apollo 16 deep drill core. These studies provided depth profiles for composition, in terms of the concentration of FeO, and relative surface exposure age (or maturity), in terms of the values of the specific FMR intensity normalized to the FeO content. For core 60009/60010, the concentration of FeO ranged from about 1.6 wt.% to 5.8 wt.% with a mean value of 4.6 wt.% and the maturity ranged from immature to mature with most of the soils being submature. A systematic decrease in maturity from the lunar surface to a depth of about 12.5 cm was observed in core section 60010. For core section 60003, the concentration of FeO ranged from about 5.2 wt.% to 7.5 wt.% with a mean value of 6.4 wt.% and the maturity ranged from submature to mature with most of the soils being mature.

Morris, R. V.↗
NASA NTRS1976

Ferromagnetic resonance studies of lunar core stratigraphy

We first review the evidence which links the characteristic ferromagnetic resonance observed in lunar fines samples with agglutinatic glass produced primarily by micrometeorite impacts and present new results on Apollo 15, 16, and 17 breccias which support this link by showing that only regolith breccias contribute significantly to the characteristic FMR intensity. We then provide a calibration of the amount of Fe metal in the form of uniformly magnetized spheres required to give our observed FMR intensities and discuss the theoretical magnetic behavior to be expected of Fe spheres as a function of size. Finally, we present FMR results on samples from every 5 mm interval in the core segments 60003, 60009, and 70009. These results lead us to suggest: (1) that secondary mixing may generally be extensive during regolith deposition so that buried regolith surfaces are hard to recognize or define; and (2) that local grinding of rocks and pebbles during deposition may lead to short scale fluctuations in grain size, composition, and apparent exposure age of samples.

Housley, R. M.↗
DOE OSTI2024

In situ electric-field control of ferromagnetic resonance in the low-loss organic-based ferrimagnet V[TCNE] x ∼2

We demonstrate indirect electric-field control of ferromagnetic resonance (FMR) in devices that integrate the low-loss, molecule-based, room-temperature ferrimagnet vanadium tetracyanoethylene (V[TCNE]x∼2) mechanically coupled to PMN-PT piezoelectric transducers. Upon straining the V[TCNE]x films, the FMR frequency is tuned by more than 6 times the resonant linewidth with no change in Gilbert damping for samples with α = 6.5 × 10−5. We show this tuning effect is due to a strain-dependent magnetic anisotropy in the films and find the magnetoelastic coefficient |λs| ∼ (1–4.4) ppm, backed by theoretical predictions from density-functional theory calculations and magnetoelastic theory. Noting the rapidly expanding application space for strain-tuned FMR, we define a new metric for magnetostrictive materials, magnetostrictive agility, given by the ratio of the magnetoelastic coefficient to the FMR linewidth. This agility allows for a direct comparison between magnetostrictive materials in terms of their comparative efficacy for magnetoelectric applications requiring ultra-low loss magnetic resonance modulated by strain. With this metric, we show V[TCNE]x is competitive with other magnetostrictive materials, including YIG and Terfenol-D. This combination of ultra-narrow linewidth and magnetostriction, in a system that can be directly integrated into functional devices without requiring heterogeneous integration in a thin film geometry, promises unprecedented functionality for electric-field tuned microwave devices ranging from low-power, compact filters and circulators to emerging applications in quantum information science and technology.

Materials Science↗
NASA NTRS1983

Ferromagnetic resonance and magnetic properties of ALHA 81005

Seven chips of primarily matrix material from the Antarctic meteorite ALHA 81005 were analyzed by ferromagnetic resonance (FMR) and magnetic hysteresis techniques. The FMR spectra of two chips have a resonance at g of about 2.1 that resembles the g of about 2.1 resonance that is characteristic of lunar soils. Thus the FMR spectra are consistent with the lunar regolith being a progenitor for the matrix material. For the two chips, the FMR surface exposure (maturity) index was about 5 units, which is equivalent to a value for an immature lunar soil. The total concentration of metallic iron is on the order of 0.11 equivalent wt. pct, which is within the observed range for Apollo 16 rocks and soils.

Morris, R. V.↗
NASA NTRS1975

Petrographic and ferromagnetic resonance studies of experimentally shocked regolith analogs

Studies of porous aggregates of a regolith analog system composed of a 50:50-wt% mixture of labradorite and bronzite shocked at approximately 100-kbar intervals up to approximately 500 kbar are described, and characteristics of the well-indurated 'rock' formed at all pressures are reported. Ferromagnetic resonance studies of diopside and bronzite that were shocked at approximately 500 kbar are also reported. The formation of metallic particles in the superparamagnetic and single-domain size range as well as the metal fractionation are characterized, and the results suggest that the superparamagnetic and single-domain metallic particles in lunar soils may be produced by shock-induced dissemination of meteoritic and indigenous metal.

Gibbons, R. V.↗