The point-like nature and exquisite magnetic field sensitivity of the nitrogen vacancy (NV) center in diamond can provide information about the inner workings of magnetic nanocircuits in complement with traditional transport techniques. Here, we use a single NV in bulk diamond to probe the stray field of a ferromagnetic nanowire controlled by spin transfer (ST) torques. We first report an unambiguous measurement of ST tuned, parametrically driven, large-amplitude magnetic oscillations. At the same time, we demonstrate that such magnetic oscillations alone can directly drive NV spin transitions, providing a potential new means of control. Finally, we use the NV as a local noise thermometer, observing strong ST damping of the stray field noise, consistent with magnetic cooling from room temperature to ∼150 K.
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http://dx.doi.org/10.1021/acs.nanolett.8b03012 | DOI Listing |
Nat Nanotechnol
January 2025
Max Planck Institute for Microstructure Physics, Halle (Saale), Germany.
Magnetic random-access memory that uses magnetic tunnel junction memory cells is a high-performance, non-volatile memory technology that goes beyond traditional charge-based memories. Today, its speed is limited by the high magnetization of the memory storage layer. Here we prepare magnetic tunnel junction memory devices with a low magnetization ferrimagnetic Heusler alloy MnGe as the memory storage layer on technologically relevant amorphous substrates using a combination of a nitride seed layer and a chemical templating layer.
View Article and Find Full Text PDFJ Magn Reson
December 2024
Department of Medicine, University of Alberta, Canada; Department of Biochemistry, University of Alberta, Canada. Electronic address:
Solution NMR studies of large systems are hampered by rapid signal decay. We hereby introduce ROCSY (relaxation-optimized total correlation spectroscopy), which maximizes transfer efficiency across J-coupling-connected spin networks by minimizing the amount of time magnetization spends in the transverse plane. Hard pulses are substituted into the Clean-CITY TOCSY pulse element first developed by Ernst and co-workers, allowing for longer delays in which magnetization is aligned along the z-axis.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Center for Cosmology and Particle Physics, Department of Physics, New York University, New York, New York 10003, USA.
We show that the Veneziano amplitude of string theory is the unique solution to an analytically solvable bootstrap problem. Uniqueness follows from two assumptions: faster than power-law falloff in high-energy scattering and the existence of some infinite sequence in momentum transfer at which higher-spin exchanges cancel. The string amplitude-including the mass spectrum-is an output of this bootstrap.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructures, College of Engineering and Applied Sciences, Nanjing University, No. 22 Hankou Road, Nanjing, Jiangsu 210093, People's Republic of China.
Water electrolysis suffers from electron transfer barriers during oxygen evolution reactions, which are spin-related for magnetic materials. Here, the electron transfer at the Fe_{64}Ni_{36}-FeNiO_{x}H_{y} interface is effectively accelerated when the electrode is heated to trigger the Invar effect in Fe_{64}Ni_{36} Invar alloy, providing more unoccupied orbitals as electron transfer channels without pairing energy. As a result of thermally stimulated changes in electronic states, Fe_{64}Ni_{36}/FeNiO_{x}H_{y} achieved a cascaded oxidation of the catalytic center and water.
View Article and Find Full Text PDFJ Chem Theory Comput
January 2025
HUN-REN Wigner Research Centre for Physics, P.O. Box 49, H-1525 Budapest, Hungary.
The assessment of electronic structure descriptions utilized in the simulation of the ultrafast excited-state dynamics of Fe(II) complexes is presented. Herein, we evaluate the performance of the RPBE, OPBE, BLYP, B3LYP, B3LYP*, PBE0, TPSSh, CAM-B3LYP, and LC-BLYP (time-dependent) density functional theory (DFT/TD-DFT) methods in full-dimensional trajectory surface hopping (TSH) simulations carried out on linear vibronic coupling (LVC) potentials. We exploit the existence of time-resolved X-ray emission spectroscopy (XES) data for the [Fe(bmip)] and [Fe(terpy)] prototypes for dynamics between metal-to-ligand charge-transfer (MLCT) and metal-centered (MC) states, which serve as a reference to benchmark the calculations (bmip = 2,6-bis(3-methyl-imidazole-1-ylidine)-pyridine, terpy = 2,2':6',2″-terpyridine).
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