scholarly journals Ultralow magnetic damping of a common metallic ferromagnetic film

2021 ◽  
Vol 7 (4) ◽  
pp. eabc5053
Author(s):  
Yanping Wei ◽  
Wenjing Zhang ◽  
Bing Lv ◽  
Xia Xu ◽  
Shibo Xi ◽  
...  
Keyword(s):  
Electron Scattering ◽  
Linear Response ◽  
Ferromagnetic Film ◽  
Surface Model ◽  
Magnetic Damping ◽  
Quantitative Calculation ◽  
Theoretical Approaches ◽  
Damping Parameter ◽  
Metallic Ferromagnet ◽  
Damping Model

For most magnetic materials, ultralow damping is of key importance for spintronic and spin-orbitronic applications, but the number of materials suitable for charge-based spintronic and spin-orbitronic applications is limited because of magnon-electron scattering. However, some theoretical approaches including the breathing Fermi surface model, generalized torque correlation model, scattering theory, and linear response damping model have been presented for the quantitative calculation of transition metallic ferromagnet damping. For the Fe-Co alloy, an ultralow intrinsic damping approaching 10−4 was first theoretically predicted using a linear response damping model by Mankovsky et al. and then experimentally observed by Schoen et al. Here, we experimentally report a damping parameter approaching 1.5 × 10−3 for traditional fundamental iron aluminide (FeAl) soft ferromagnets that is comparable to those of 3d transition metallic ferromagnets and explain this phenomenon based on the principle of minimum electron density of states.

scholarly journals Positron Scattering from Atoms and Molecules

Atoms ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 29 ◽  
Author(s):  
Sultana N. Nahar ◽  
Bobby Antony
Keyword(s):  
Cross Section ◽  
Electron Scattering ◽  
Cross Sections ◽  
Optical Potential ◽  
Inert Gases ◽  
Positron Impact ◽  
Positron Scattering ◽  
Atoms And Molecules ◽  
Section Data ◽  
Theoretical Approaches

A review on the positron scattering from atoms and molecules is presented in this article. The focus on positron scattering studies is on the rise due to their presence in various fields and application of cross section data in such environments. Positron scattering is usually investigated using theoretical approaches that are similar to those for electron scattering, being its anti-particle. However, most experimental or theoretical studies are limited to the investigation of electron and positron scattering from inert gases, single electron systems and simple or symmetric molecules. Optical potential and polarized orbital approaches are the widely used methods for investigating positron scattering from atoms. Close coupling approach has also been used for scattering from atoms, but for lighter targets with low energy projectiles. The theoretical approaches have been quite successful in predicting cross sections and agree reasonably well with experimental measurements. The comparison is generally good for electrons for both elastic and inelastic scatterings cross sections, while spin polarization has been critical due to its sensitive perturbing interaction. Positron scattering cross sections show relatively less features than that of electron scattering. The features of positron impact elastic scattering have been consistent with experiment, while total cross section requires significant improvement. For scattering from molecules, utilization of both spherical complex optical potential and R-matrix methods have proved to be efficient in predicting cross sections in their respective energy ranges. The results obtained shows reasonable comparison with most of the existing data, wherever available. In the present article we illustrate these findings with a list of comprehensive references to data sources, albeit not exhaustive.

Tuning of the Magnetic Damping Parameter by Varying Cr Composition in Fe1–x Cr x Alloy

2020 ◽  
Vol 37 (10) ◽  
pp. 107502
Author(s):  
Mao Yang ◽  
Xianyang Lu ◽  
Bo Liu ◽  
Xuezhong Ruan ◽  
Junran Zhang ◽  
...  
Keyword(s):  
Magnetic Damping ◽  
Damping Parameter

Novel theoretical approaches to small-angle electron scattering

1999 ◽  
Vol 487 (1-2) ◽  
pp. 57-65
Author(s):  
Z Felfli ◽  
D Bessis ◽  
A Msezane
Keyword(s):  
Electron Scattering ◽  
Small Angle ◽  
Theoretical Approaches

scholarly journals Tuning of the intrinsic magnetic damping parameter in epitaxial CoNi(001) films : Role of the band-filling effect

2019 ◽  
Vol 100 (2) ◽  
Author(s):  
S. J. Xu ◽  
J. Y. Shi ◽  
Y. S. Hou ◽  
Z. Zheng ◽  
H. B. Zhao ◽  
...  
Keyword(s):  
Magnetic Damping ◽  
Damping Parameter ◽  
Band Filling

scholarly journals Magnetoelastic interactions and magnetic damping in Co2Fe0.4Mn0.6Si and Co2FeGa0.5Ge0.5 Heusler alloys thin films for spintronic applications

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
O. M. Chumak ◽  
A. Pacewicz ◽  
A. Lynnyk ◽  
B. Salski ◽  
T. Yamamoto ◽  
...  
Keyword(s):  
Thin Films ◽  
Magnetic Properties ◽  
Layer Thickness ◽  
Heusler Alloys ◽  
Magnetic Layer ◽  
Spin Pumping ◽  
Magnetic Damping ◽  
Spintronic Devices ◽  
Damping Parameter ◽  
High Spin Polarization

AbstractCo2Fe0.4Mn0.6Si (CFMS) and Co2FeGa0.5Ge0.5 (CFGG) Heusler alloys are among the most promising thin film materials for spintronic devices due to a high spin polarization, low magnetic damping and giant/tunneling magnetoresistance ratios. Despite numerous investigations of Heusler alloys magnetic properties performed up to now, magnetoelastic effects in these materials remain not fully understood; due to quite rare studies of correlations between magnetoelastic and other magnetic properties, such as magnetic dissipation or magnetic anisotropy. In this research we have investigated epitaxial CFMS and CFGG Heusler alloys thin films of thickness in the range of 15–50 nm. We have determined the magnetoelastic tensor components and magnetic damping parameters as a function of the magnetic layer thickness. Magnetic damping measurements revealed the existence of non-Gilbert dissipation related contributions, including two-magnon scattering and spin pumping phenomena. Magnetoelastic constant B11 values and the effective magnetic damping parameter αeff values were found to be in the range of − 6 to 30 × 106 erg/cm3 and between 1 and 12 × 10–3, respectively. The values of saturation magnetostriction λS for CFMS Heusler alloy thin films were also obtained using the strain modulated ferromagnetic resonance technique. The correlation between αeff and B11, depending on magnetic layer thickness was determined based on the performed investigations of the above mentioned magnetic properties.

Effect of nanoparticle size on magnetic damping parameter in Co92Zr8 soft magnetic films

2012 ◽  
Vol 324 (18) ◽  
pp. 2840-2843 ◽  
Author(s):  
Gaoxue Wang ◽  
Chunhui Dong ◽  
Changjun Jiang ◽  
Guozhi Chai ◽  
Desheng Xue
Keyword(s):  
Magnetic Films ◽  
Nanoparticle Size ◽  
Soft Magnetic ◽  
Magnetic Damping ◽  
Damping Parameter ◽  
Soft Magnetic Films

scholarly journals Ultra-low magnetic damping of a metallic ferromagnet

2016 ◽  
Vol 12 (9) ◽  
pp. 839-842 ◽  
Author(s):  
Martin A. W. Schoen ◽  
Danny Thonig ◽  
Michael L. Schneider ◽  
T. J. Silva ◽  
Hans T. Nembach ◽  
...  
Keyword(s):  
Magnetic Damping ◽  
Metallic Ferromagnet

scholarly journals FUNDAMENTAL CONSTRAINTS ON LINEAR RESPONSE THEORIES OF FERMI SUPERFLUIDS ABOVE AND BELOW Tc

2013 ◽  
Vol 27 (16) ◽  
pp. 1330010 ◽  
Author(s):  
HAO GUO ◽  
CHIH-CHUN CHIEN ◽  
YAN HE ◽  
K. LEVIN
Keyword(s):  
Gauge Invariance ◽  
Linear Response ◽  
Random Phase ◽  
Mean Field ◽  
Linear Response Theory ◽  
Bcs Theory ◽  
Einstein Condensation ◽  
Sum Rule ◽  
Many Body Theory ◽  
Theoretical Approaches

We present fundamental constraints required for a consistent linear response theory of fermionic superfluids and address temperatures both above and below the transition temperature Tc. We emphasize two independent constraints, one associated with gauge invariance (and the related Ward identity) and another associated with the compressibility sum rule, both of which are satisfied in strict BCS theory. However, we point out that it is the rare many body theory which satisfies both of these. Indeed, well studied quantum Hall systems and random-phase approximations to the electron gas are found to have difficulties with meeting these constraints. We summarize two distinct theoretical approaches which are, however, demonstrably compatible with gauge invariance and the compressibility sum rule. The first of these involves an extension of BCS theory to a mean field description of the BCS-Bose Einstein condensation crossover. The second is the simplest Nozieres Schmitt–Rink (NSR) treatment of pairing correlations in the normal state. As a point of comparison we focus on the compressibility κ of each and contrast the predictions above Tc. We note here that despite the compliance with sum rules, this NSR based scheme leads to an unphysical divergence in κ at the transition. Because of the delicacy of the various consistency requirements, the results of this paper suggest that avoiding this divergence may repair one problem while at the same time introducing others.

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