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Results for “Fe-Ge”

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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14 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Chiral Spin Textures in Amorphous Iron–Germanium Thick Films

Topological solitary fields, such as magnetic and polar skyrmions, are envisioned to revolutionize microelectronics. These configurations have been stabilized in solid-state materials with a global inversion symmetry breaking, which translates in magnetic materials into a vector spin exchange known as the Dzyaloshinskii-Moriya interaction (DMI), as well as spin chirality selection and isotropic solitons. This work reports experimental evidence of 3D chiral spin textures, such as helical spins and skyrmions with different chirality and topological charge, stabilized in amorphous Fe-Ge thick films. Overall, these results demonstrate that structurally and chemically disordered materials with a random DMI can resemble inversion symmetry broken systems with similar magnetic properties, moments, and states. Disordered systems are distinguished from systems with global inversion symmetry breaking by their degenerate spin chirality that allows for forming isotropic and anisotropic topological spin textures at remanence, while offering greater flexibility in materials synthesis, voltage, and strain manipulation.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Spin-Charge-Lattice Coupling across the Charge Density Wave Transition in a Kagome Lattice Antiferromagnet

Understanding spin and lattice excitations in a metallic magnetic ordered system forms the basis to unveil the magnetic and lattice exchange couplings and their interactions with itinerant electrons. Kagome lattice antiferromagnet FeGe is interesting because it displays a rare charge density wave (CDW) deep inside the antiferromagnetic ordered phase that interacts with the magnetic order. Here, we use neutron scattering to study the evolution of spin and lattice excitations across the CDW transition 𝑇 CDW in FeGe. While spin excitations below ∼100 meV can be well described by spin waves of a spin-1 Heisenberg Hamiltonian, spin excitations at higher energies are centered around the Brillouin zone boundary and extend up to ∼180 meV consistent with quasiparticle excitations across spin-polarized electron-hole Fermi surfaces. Furthermore, 𝑐-axis spin wave dispersion and Fe-Ge optical phonon modes show a clear hardening below 𝑇 CDW due to spin-charge-lattice coupling but with no evidence of a phonon Kohn anomaly. By comparing our experimental results with density functional theory calculations in absolute units, we conclude that FeGe is a Hund’s metal in the intermediate correlated regime where magnetism has contributions from both itinerant and localized electrons arising from spin polarized electronic bands near the Fermi level.

charge density waves↗
DOE OSTI2023

Visualizing the Effect of Oxidation on Magnetic Domain Behavior of Nanoscale Fe 3 GeTe 2 for Applications in Spintronics

Magnetic van der Waals (vdW) materials offer an opportunity to design heterostructures that will lead to exotic functionalities that arise from interfacial interaction. In addition to coupling to different vdW materials, the naturally oxidized surface layer of a vdW material also forms a heterostructure with its bulk film, giving rise to intriguing phenomena. Here, we directly observe the impact of oxidation on the magnetic domains, namely, magnetic stripe domain and skyrmions, in a nanoscale Fe 3 GeTe 2 flake using cryo Lorentz transmission electron microscopy. After the Fe 3 GeTe 2 is exposed to ambient conditions, partial oxidation leads to an increase in the density of skyrmions even under zero magnetic field. Complete oxidation leads to a loss of the magnetic domain structure. We observe a gradual change in Fe 3 GeTe 2 from single crystal to amorphous as the oxidation increases. The oxidized Fe 3 GeTe 2 primarily consists of iron oxide, which could be antiferromagnetic in nature. We hypothesize that the interfacial interaction between these surface antiferromagnetic oxides and the bulk ferromagnetic Fe 3 GeTe 2 , as well as the effect of interfacial roughness, leads to the increase in Néel skyrmion creation. Furthermore, this work opens a path to harness controlled oxidation as a build block to create dense skyrmion lattices without the need for an external magnetic field, leading to potential future applications in spintronic devices.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Fe3Ge by Materials Project

Fe3Ge is Uranium Silicide structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. Fe is bonded to eight equivalent Fe and four equivalent Ge atoms to form FeFe8Ge4 cuboctahedra that share corners with twelve equivalent FeFe8Ge4 cuboctahedra, edges with eight equivalent GeFe12 cuboctahedra, edges with sixteen equivalent FeFe8Ge4 cuboctahedra, faces with four equivalent GeFe12 cuboctahedra, and faces with fourteen equivalent FeFe8Ge4 cuboctahedra. All Fe–Fe bond lengths are 2.57 Å. All Fe–Ge bond lengths are 2.57 Å. Ge is bonded to twelve equivalent Fe atoms to form GeFe12 cuboctahedra that share corners with twelve equivalent GeFe12 cuboctahedra, edges with twenty-four equivalent FeFe8Ge4 cuboctahedra, faces with six equivalent GeFe12 cuboctahedra, and faces with twelve equivalent FeFe8Ge4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Fe2Ge by Materials Project

Fe2Ge crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Fe sites. In the first Fe site, Fe is bonded in a 8-coordinate geometry to eight Fe and six equivalent Ge atoms. There are two shorter (2.50 Å) and six longer (2.69 Å) Fe–Fe bond lengths. All Fe–Ge bond lengths are 2.69 Å. In the second Fe site, Fe is bonded to six equivalent Fe and five equivalent Ge atoms to form a mixture of distorted face and corner-sharing FeFe6Ge5 trigonal bipyramids. There are three shorter (2.39 Å) and two longer (2.50 Å) Fe–Ge bond lengths. Ge is bonded in a 5-coordinate geometry to eleven Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Fe3Ge by Materials Project

Fe3Ge is alpha bismuth trifluoride structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. there are two inequivalent Fe sites. In the first Fe site, Fe is bonded in a 8-coordinate geometry to eight equivalent Fe and six equivalent Ge atoms. All Fe–Fe bond lengths are 2.49 Å. All Fe–Ge bond lengths are 2.87 Å. In the second Fe site, Fe is bonded in a distorted body-centered cubic geometry to four equivalent Fe and four equivalent Ge atoms. All Fe–Ge bond lengths are 2.49 Å. Ge is bonded in a distorted body-centered cubic geometry to fourteen Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Fe3Ge by Materials Project

Fe3Ge is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are three inequivalent Fe sites. In the first Fe site, Fe is bonded to eight Fe and four equivalent Ge atoms to form FeFe8Ge4 cuboctahedra that share corners with four equivalent GeFe12 cuboctahedra, corners with fourteen FeFe8Ge4 cuboctahedra, edges with six equivalent GeFe12 cuboctahedra, edges with twelve FeFe8Ge4 cuboctahedra, faces with four equivalent GeFe12 cuboctahedra, and faces with sixteen FeFe8Ge4 cuboctahedra. There are a spread of Fe–Fe bond distances ranging from 2.51–2.64 Å. There are two shorter (2.57 Å) and two longer (2.60 Å) Fe–Ge bond lengths. In the second Fe site, Fe is bonded to eight Fe and four equivalent Ge atoms to form FeFe8Ge4 cuboctahedra that share corners with four equivalent GeFe12 cuboctahedra, corners with fourteen FeFe8Ge4 cuboctahedra, edges with six equivalent GeFe12 cuboctahedra, edges with twelve FeFe8Ge4 cuboctahedra, faces with four equivalent GeFe12 cuboctahedra, and faces with sixteen FeFe8Ge4 cuboctahedra. There are one shorter (2.51 Å) and one longer (2.64 Å) Fe–Fe bond lengths. There are two shorter (2.57 Å) and two longer (2.60 Å) Fe–Ge bond lengths. In the third Fe site, Fe is bonded to eight Fe and four equivalent Ge atoms to form FeFe8Ge4 cuboctahedra that share corners with four equivalent GeFe12 cuboctahedra, corners with fourteen FeFe8Ge4 cuboctahedra, edges with six equivalent GeFe12 cuboctahedra, edges with twelve FeFe8Ge4 cuboctahedra, faces with four equivalent GeFe12 cuboctahedra, and faces with sixteen FeFe8Ge4 cuboctahedra. There are two shorter (2.57 Å) and two longer (2.60 Å) Fe–Ge bond lengths. Ge is bonded to twelve Fe atoms to form GeFe12 cuboctahedra that share corners with six equivalent GeFe12 cuboctahedra, corners with twelve FeFe8Ge4 cuboctahedra, edges with eighteen FeFe8Ge4 cuboctahedra, faces with eight equivalent GeFe12 cuboctahedra, and faces with twelve FeFe8Ge4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on FeGe2 by Materials Project

FeGe2 is Khatyrkite structured and crystallizes in the tetragonal I4/mcm space group. The structure is three-dimensional. Fe is bonded in a 10-coordinate geometry to two equivalent Fe and eight equivalent Ge atoms. Both Fe–Fe bond lengths are 2.47 Å. All Fe–Ge bond lengths are 2.55 Å. Ge is bonded in a 5-coordinate geometry to four equivalent Fe and one Ge atom. The Ge–Ge bond length is 2.63 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on FeGe by Materials Project

FeGe crystallizes in the cubic P2_13 space group. The structure is three-dimensional. Fe is bonded in a 7-coordinate geometry to seven equivalent Ge atoms. There are a spread of Fe–Ge bond distances ranging from 2.38–2.62 Å. Ge is bonded in a 7-coordinate geometry to seven equivalent Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on FeGe by Materials Project

FeGe crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Fe is bonded in a 10-coordinate geometry to four equivalent Fe and six Ge atoms. All Fe–Fe bond lengths are 2.49 Å. There are four shorter (2.48 Å) and two longer (2.49 Å) Fe–Ge bond lengths. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded in a 6-coordinate geometry to six equivalent Fe atoms. In the second Ge site, Ge is bonded in a hexagonal planar geometry to six equivalent Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on FeGe by Materials Project

FeGe crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are three inequivalent Fe sites. In the first Fe site, Fe is bonded in a 6-coordinate geometry to four Fe and six Ge atoms. There are two shorter (2.45 Å) and two longer (2.64 Å) Fe–Fe bond lengths. There are four shorter (2.47 Å) and two longer (2.49 Å) Fe–Ge bond lengths. In the second Fe site, Fe is bonded in a 6-coordinate geometry to four Fe and six Ge atoms. Both Fe–Fe bond lengths are 2.68 Å. There are two shorter (2.41 Å) and four longer (2.43 Å) Fe–Ge bond lengths. In the third Fe site, Fe is bonded in a 11-coordinate geometry to four Fe and seven Ge atoms. Both Fe–Fe bond lengths are 2.48 Å. There are a spread of Fe–Ge bond distances ranging from 2.44–2.79 Å. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded in a 6-coordinate geometry to six Fe and two equivalent Ge atoms. Both Ge–Ge bond lengths are 2.73 Å. In the second Ge site, Ge is bonded in a 7-coordinate geometry to seven Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Fe13Ge3 by Materials Project

Fe13Ge3 crystallizes in the orthorhombic Pmmm space group. The structure is three-dimensional. there are six inequivalent Fe sites. In the first Fe site, Fe is bonded in a distorted body-centered cubic geometry to five Fe and three Ge atoms. There are a spread of Fe–Fe bond distances ranging from 2.46–2.50 Å. All Fe–Ge bond lengths are 2.49 Å. In the second Fe site, Fe is bonded in a 8-coordinate geometry to ten Fe and four Ge atoms. Both Fe–Fe bond lengths are 2.86 Å. All Fe–Ge bond lengths are 2.87 Å. In the third Fe site, Fe is bonded in a distorted body-centered cubic geometry to fourteen Fe atoms. All Fe–Fe bond lengths are 2.87 Å. In the fourth Fe site, Fe is bonded in a 8-coordinate geometry to ten Fe and four Ge atoms. There are two shorter (2.86 Å) and two longer (2.87 Å) Fe–Ge bond lengths. In the fifth Fe site, Fe is bonded in a 8-coordinate geometry to ten Fe and four Ge atoms. There are two shorter (2.86 Å) and two longer (2.87 Å) Fe–Ge bond lengths. In the sixth Fe site, Fe is bonded in a 8-coordinate geometry to eight equivalent Fe and six Ge atoms. There are two shorter (2.86 Å) and four longer (2.87 Å) Fe–Ge bond lengths. There are three inequivalent Ge sites. In the first Ge site, Ge is bonded in a distorted body-centered cubic geometry to fourteen Fe atoms. In the second Ge site, Ge is bonded in a distorted body-centered cubic geometry to fourteen Fe atoms. In the third Ge site, Ge is bonded in a distorted body-centered cubic geometry to fourteen Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Fe2Ge by Materials Project

Fe2Ge crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Fe is bonded in a 11-coordinate geometry to five equivalent Fe and six equivalent Ge atoms. There are three shorter (2.40 Å) and two longer (2.63 Å) Fe–Fe bond lengths. All Fe–Ge bond lengths are 2.74 Å. Ge is bonded in a 12-coordinate geometry to twelve equivalent Fe and two equivalent Ge atoms. Both Ge–Ge bond lengths are 2.63 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Fe6Ge5 by Materials Project

Fe6Ge5 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are five inequivalent Fe sites. In the first Fe site, Fe is bonded in a 11-coordinate geometry to five Fe and six Ge atoms. There are a spread of Fe–Fe bond distances ranging from 2.37–2.74 Å. There are a spread of Fe–Ge bond distances ranging from 2.41–2.89 Å. In the second Fe site, Fe is bonded in a 5-coordinate geometry to five Fe and six Ge atoms. There are a spread of Fe–Fe bond distances ranging from 2.59–2.71 Å. There are a spread of Fe–Ge bond distances ranging from 2.49–2.69 Å. In the third Fe site, Fe is bonded in a 7-coordinate geometry to two equivalent Fe and seven Ge atoms. Both Fe–Fe bond lengths are 2.77 Å. There are a spread of Fe–Ge bond distances ranging from 2.42–2.66 Å. In the fourth Fe site, Fe is bonded in a 12-coordinate geometry to four Fe and six Ge atoms. Both Fe–Fe bond lengths are 2.47 Å. There are a spread of Fe–Ge bond distances ranging from 2.43–2.47 Å. In the fifth Fe site, Fe is bonded in a 12-coordinate geometry to six Fe and six Ge atoms. There are a spread of Fe–Ge bond distances ranging from 2.44–2.51 Å. There are four inequivalent Ge sites. In the first Ge site, Ge is bonded in a 9-coordinate geometry to nine Fe atoms. In the second Ge site, Ge is bonded in a 7-coordinate geometry to seven Fe atoms. In the third Ge site, Ge is bonded in a 7-coordinate geometry to seven Fe atoms. In the fourth Ge site, Ge is bonded in a 7-coordinate geometry to seven Fe atoms.

36 MATERIALS SCIENCE↗