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Title: Magnetization fluctuations in nominally stable ferromagnetic materials

 [1];  [1];  [2];  [2]; ORCiD logo [1]; ORCiD logo [1]
  1. Los Alamos National Laboratory
  2. NIST
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Laboratory Directed Research and Development (LDRD) Program
OSTI Identifier:
Report Number(s):
DOE Contract Number:
Resource Type:
Resource Relation:
Conference: Science in "3" ; 2017-06-07 - 2017-06-07 ; Los Alamos, New Mexico, United States
Country of Publication:
United States
High Magnetic Field Science; Magnetic nanostructures, neuromorphic computing, magnetic fluctuations, noise

Citation Formats

Balk, Andrew, Li, Fuxiang, Gilbert, Ian, Unguris, John, Sinitsyn, Nikolai, and Crooker, Scott A. Magnetization fluctuations in nominally stable ferromagnetic materials. United States: N. p., 2017. Web.
Balk, Andrew, Li, Fuxiang, Gilbert, Ian, Unguris, John, Sinitsyn, Nikolai, & Crooker, Scott A. Magnetization fluctuations in nominally stable ferromagnetic materials. United States.
Balk, Andrew, Li, Fuxiang, Gilbert, Ian, Unguris, John, Sinitsyn, Nikolai, and Crooker, Scott A. Thu . "Magnetization fluctuations in nominally stable ferromagnetic materials". United States. doi:.
title = {Magnetization fluctuations in nominally stable ferromagnetic materials},
author = {Balk, Andrew and Li, Fuxiang and Gilbert, Ian and Unguris, John and Sinitsyn, Nikolai and Crooker, Scott A.},
abstractNote = {},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Jun 01 00:00:00 EDT 2017},
month = {Thu Jun 01 00:00:00 EDT 2017}

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  • Using the itinerant model of magnetic moment in ferromagnetic metals, the resistivity anomalies near the Curie temperature T/sub c/ was investigated. The short-range magnetization fluctuations have been taken into account in calculating the spin correlation function in the paramagnetic region. The mean free path is considered to be comparable with the correlation length and to be temperature dependent near T/sub c/. A critical exponent is introduced for the mean free path and its value is established to be not smaller than 1/2. The resistivity is found to be continuous through T/sub c/. The temperature derivative of the resistivity is foundmore » to be divergent linearly and positively near and above T/sub c/. These results confirm the phase transition nature of the resistivity anomalies of the ferromagnetic metals near T/sub c/ and show that the short-range order must also exist in the itinerant model of the magnetic electrons.« less
  • Magnetization measurements on an amorphous ferromagnetic alloy Fe[sub 78](SiB)[sub 22] have been made over the temperature range from 5 to 295K and in fields to 5T, using a SQUID magnetometer and a superconducting magnet. As-received and field-annealed samples were measured. Having data over a range of temperatures allows the spin-wave contribution to the magnetization to be determined, and then subtracted. When the spin-wave contribution is removed, a substantial high-field susceptibility remains, which is independent of temperature. Attempts to fit the corrected curves to one of two theoretical equations were not conclusive, but the best fit seems to be to Mmore » = M[sub 0] + aH[sup [minus]0.5] + bH. The annealing treatment has no significant effect on the high-field magnetization.« less
  • Analysis of neutron-diffraction data on the compound (Ho/sub 0/./sub 6/Er/sub 0/./sub 4/)Rh/sub 4/B/sub 4/ indicates that the Curie temperature is depressed by about 0.2 K due to the occurrence of superconductivity, in agreement with theoretical predictions. The temperature dependence of the specific heat in the vicinity of the first-order reentrant superconducting - ferromagnetic transition was computed by means of a simple model from the temperature dependence of the spontaneous magnetization of the Ho ions and was found to be in good agreement with the experimental data.
  • Recently experimental techniques, such as magnetic force microscopy (MFM), have enabled the magnetic state of individual sub-micron particles to be resolved. Motivated by these experimental developments, the authors use Monte Carlo simulations of two-dimensional kinetic Ising ferromagnets to study the magnetic relaxation in a negative applied field of a grain with an initial magnetization m{sub 0} = + 1. They use classical droplet theory to predict the functional forms for some quantities which can be observed by MFM. An example is the probability that the magnetization is positive, which is a function of time, field, grain size, and grain dimensionality.more » The qualitative agreement between experiments and their simulations of switching in individual single-domain ferromagnets indicates that the switching mechanism in such particles may involve local nucleation and subsequent growth of droplets of the stable phase.« less