skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: A proposed method for electronic feedback compensation of damping in ferromagnetic resonance

Abstract

Here, we propose an experimental technique for extending feedback compensation of dissipative radiation used in nuclear magnetic resonance (NMR) to encompass ferromagnetic resonance (FMR). This method uses a balanced microwave power detector whose output is phase shifted π/2, amplified, and fed back to drive precession. Using classical control theory, we predict an electronically controllable narrowing of field swept FMR line-widths. This technique is predicted to compensate other sources of spin dissipation in addition to radiative loss.

Authors:
 [1];  [2]
  1. SLAC National Accelerator Lab., Menlo Park, CA (United States)
  2. Argonne National Lab. (ANL), Lemont, IL (United States)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
National Institutes of Health (NIH); USDOE
OSTI Identifier:
1379174
Alternate Identifier(s):
OSTI ID: 1410452
Grant/Contract Number:
AC02-06CH11357; AC02-76SF00515
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Magnetism and Magnetic Materials
Additional Journal Information:
Journal Volume: 443; Journal Issue: C; Journal ID: ISSN 0304-8853
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Zohar, S., and Sterbinsky, G. E. A proposed method for electronic feedback compensation of damping in ferromagnetic resonance. United States: N. p., 2017. Web. doi:10.1016/j.jmmm.2017.07.030.
Zohar, S., & Sterbinsky, G. E. A proposed method for electronic feedback compensation of damping in ferromagnetic resonance. United States. doi:10.1016/j.jmmm.2017.07.030.
Zohar, S., and Sterbinsky, G. E. Mon . "A proposed method for electronic feedback compensation of damping in ferromagnetic resonance". United States. doi:10.1016/j.jmmm.2017.07.030.
@article{osti_1379174,
title = {A proposed method for electronic feedback compensation of damping in ferromagnetic resonance},
author = {Zohar, S. and Sterbinsky, G. E.},
abstractNote = {Here, we propose an experimental technique for extending feedback compensation of dissipative radiation used in nuclear magnetic resonance (NMR) to encompass ferromagnetic resonance (FMR). This method uses a balanced microwave power detector whose output is phase shifted π/2, amplified, and fed back to drive precession. Using classical control theory, we predict an electronically controllable narrowing of field swept FMR line-widths. This technique is predicted to compensate other sources of spin dissipation in addition to radiative loss.},
doi = {10.1016/j.jmmm.2017.07.030},
journal = {Journal of Magnetism and Magnetic Materials},
number = C,
volume = 443,
place = {United States},
year = {Mon Jul 10 00:00:00 EDT 2017},
month = {Mon Jul 10 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on July 10, 2018
Publisher's Version of Record

Save / Share:
  • We determined the spin-transport properties of Pd and Pt thin films by measuring the increase in ferromagnetic resonance damping due to spin-pumping in ferromagnetic (FM)-nonferromagnetic metal (NM) multilayers with varying NM thicknesses. The increase in damping with NM thickness depends strongly on both the spin- and charge-transport properties of the NM, as modeled by diffusion equations that include both momentum- and spin-scattering parameters. We use the analytical solution to the spin-diffusion equations to obtain spin-diffusion lengths for Pt and Pd. By measuring the dependence of conductivity on NM thickness, we correlate the charge- and spin-transport parameters, and validate the applicabilitymore » of various models for momentum-scattering and spin-scattering rates in these systems: constant, inverse-proportional (Dyakanov-Perel), and linear-proportional (Elliot-Yafet). We confirm previous reports that the spin-scattering time appears to be shorter than the momentum scattering time in Pt, and the Dyakanov-Perel-like model is the best fit to the data.« less
  • The ferromagnetic resonance intrinsic field linewidth ΔH is investigated for a multilayer system such as a coupled trilayer and a spin valve structure. The magnetic coupling between two ferromagnetic layers separated by a nonmagnetic interlayer will be described by the bilinear J{sub 1} and biquadratic J{sub 2} coupling parameters. The interaction at the interface of the first ferromagnetic layer with the antiferromagnetic one is account for by the exchange anisotropy field, H{sub E}. A general formula is derived for the intrinsic linewidth ΔH. The explicit dependence of ΔH with H{sub E}, J{sub 1} and J{sub 2} will be highlighted. Analyticalmore » expressions for each mode field linewidth are found in special cases. Equivalent damping constants will be discussed.« less
  • We calculate an expression for the fine structure in the field fluctuation spectrum of a semiconductor laser in terms of accessible device parameters. We measure the spectrum of an InGaAsP DFB laser and determine the linewidth, relaxation resonance, and damping versus current. From the relation between damping and current, we determine the nonlinear gain coefficient.
  • It is suggested that under certain conditions the interpretation of ferromagnetic resonance phenomena in metals should not make use of Ohm's law because the electronic mean free path may not be negligible in comparison to an appropriately defined effective skin depth. Such conditions can exist even at moderately low temperatures provided the equivalent permeabilty is sufficiently large. The anomalous effects due to the mean free path are shown to be particularly important in spin-wave resonance, i.e. in a modified ferromagnetic resonance which is appreciably influenced by the exchange interactions existing in the skin depth. A suitable perturbation method is developedmore » for calculating these anomalous effects on the basis of Maxwell's equations and the spin-wave equation. Using a relation proposed by Reuter and Sondheimer, a simple first- order result is then obtained for the surface impedance and for the equivalent permeability derived therefrom. The limitations of the underlying physical model are pointed out, and the applicability of the theory to existing experimental results is briefly discussed.« less