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Results for “antiferromagnet”

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 541 records · Page 30
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

Antiferromagnetism of La2CuO(4-y) studied by muon-spin rotation

Zero-field spin precession of positive muons has been observed in the antiferromagnetic state of La2CuO(4-y). Sharp onsets of the sublattice magnetization are found at temperatures close to those of the susceptibility maxima of different specimens. The long-lived precession signal indicates a microscopically homogeneous distribution of spin density at each Cu atom below the Neel temperature. A combination of the present results and neutron-scattering studies indicates the ordered moment per Cu atom to be significantly less than 1 mu(B).

Uemura, Y. J.↗
NASA NTRS1989

Antiferromagnetism in Co-57-doped La2CuO(4-y) studied by Moessbauer spectroscopy

Moessbauer effect studies of Co-57-doped La2CuO(4-y) were performed at temperatures between 4.2 K and room temperature. These confirm the antiferromagnetic ordering of these compounds below room temperature. Temperature dependence of the quadrupole splitting shows that the hyperfine field is at an angle with the c-axis.

Jha, S.↗
DOE OSTI2022

Antiferromagnetic memory storage devices from magnetic transition metal dichalcogenides

Switchable antiferromagnetic (AFM) memory devices are provided based on magnetically intercalated transition metal dichalcogenides (TMDs) of the form AxMC2, where A is a magnetic element of stoichiometry x between 0 and 1, M is a transition metal of stoichiometry 1, and C is a chalcogen of stoichiometry 2. Memory storage is achieved by fabricating these materials into crosses of two or more bars and driving DC current pulses along the bars to rotate the AFM order to a fixed angle with respect to the current pulse. Application of current pulses along different bars can switch the AFM order between multiple directions. Standard resistance measurements can detect the orientation of the AFM order as high or low resistance states. The state of the device can be set by the input current pulses, and read-out by the resistance measurement, forming a non-volatile, AFM memory storage bit.

Analytis, James G.↗
DOE OSTI2021

Phase diagram of CeSb 2 from magnetostriction and magnetization measurements: Evidence for ferrimagnetic and antiferromagnetic states

Cerium diantimonide (CeSb 2 ) is one of a family of rare-earth-based magnetic materials that exhibit metamagnetism, enabling control of the magnetic ground state through an applied magnetic field. At low temperatures, CeSb 2 hosts a rich phase diagram with multiple magnetically ordered phases for many of which the order parameter is only poorly understood. In this work, we report a study of its metamagnetic properties by scanning tunneling microscopy (STM) and magnetization measurements. We use STM measurements to characterize the sample magnetostriction with subpicometer resolution from magnetic field and temperature sweeps. This allows us to directly assess the bulk phase diagram as a function of field and temperature and relate spectroscopic features from tunneling spectroscopy to bulk phases. Our magnetostriction and magnetization measurements indicate that the low-temperature ground state at zero field is ferrimagnetic. Quasiparticle interference mapping shows evidence for a reconstruction of the electronic structure close to the Fermi energy upon entering the magnetically ordered phase.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2026

Pressure‐Induced Structural and Magnetic Evolution in Layered Antiferromagnet YbMn 2 Sb 2

Electronic states under pressure exhibit unconventional spin and charge dynamics that provide a powerful route to uncover exotic phases in quantum materials. Here, we present the structural, magnetic, and electronic evolution of YbMn 2 Sb 2 under pressure. Single-crystal X-ray diffraction reveals a pressure-induced structural transition from the space group trigonal P$\overline{3}$m1 to the monoclinic P2 1 /m phase near 3.5 GPa, which remains stable up to 10 GPa. Magnetization measurements display an anomalously weak net magnetic moment and the absence of Curie–Weiss behavior up to 400 K, suggesting the formation of short-range Mn moment pairs that cancel macroscopically and subsequently evolve into long-range order upon cooling. Temperature-dependent resistivity shows semiconducting behavior with a transition at ∼119 K at ambient pressure, while pressure induces a dramatic suppression of resistance and the emergence of metallic-like temperature dependence, stabilized beyond 5 GPa. This pressure-driven semiconductor-metal transition is consistent with our density functional theory calculations, confirming the closing of the band gap under compression. Neutron diffraction under pressure identifies an incommensurate magnetic structure with antiparallel correlations between paired spins. Together, these results demonstrate how pressure-driven structural tuning and competing exchange interactions stabilize unconventional magnetic states in this low-dimensional magnetic semiconductor.

antiferromagnetic semiconductor↗
DOE OSTI2025

Scaling behavior and giant field enhancement of the thermal conductivity in the honeycomb antiferromagnet BaCo 2⁢ (AsO 4 ) 2

The layered honeycomb material BaCo 2 (AsO 4 ) 2 is of topical interest because its magnetic state is related to that of the Kitaev magnet α-RuCl 3 . Using thermal transport to probe how magnetic excitations interact with phonons in the magnetically disordered regime, we have uncovered an unusually large enhancement of the thermal conductivity κ xx in an in-plane magnetic field H. Just above the Néel temperature T N , a field of 13 T increases κ xx by a factor of ∼ 211, which is very large compared to other magnetic insulators. Interestingly, κ xx (H, T) exhibits a scaling behavior in the entire magnetically disordered region that surrounds the ordered zigzag state. The ratio Δκ xx (H, T)/κ xx (13, T), measured throughout the disordered region, collapses to a one-parameter scaling function exp(−1/gx) (where x = μ B B/k B T and g is a constant).

36 MATERIALS SCIENCE↗