scholarly journals Thermal fluctuations and longitudinal relaxation of single-domain magnetic particles at elevated temperatures

2004 ◽  
Vol 70 (21) ◽  
Author(s):  
D. A. Garanin ◽  
O. Chubykalo-Fesenko
Keyword(s):  
Magnetic Particles ◽  
Elevated Temperatures ◽  
Thermal Fluctuations ◽  
Single Domain ◽  
Longitudinal Relaxation

scholarly journals Integrated Magnetic Analyses for the Discrimination of Urban and Industrial Dusts

Minerals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1056
Author(s):  
Beata Górka-Kostrubiec ◽  
Tadeusz Magiera ◽  
Katarzyna Dudzisz ◽  
Sylwia Dytłow ◽  
Małgorzata Wawer ◽  
...  
Keyword(s):  
Grain Size ◽  
Magnetic Particles ◽  
Steel Production ◽  
Hysteresis Loops ◽  
Street Dust ◽  
Single Domain ◽  
Magnetic Fraction ◽  
Magnetic Methods ◽  
Urban Dusts ◽  
Traffic Related Pollution

Industrial and urban dusts were characterized by investigating their magnetic properties. Topsoil composed of technogenic magnetic particles (TMP) originating from areas affected by three ironworks, street dust mainly composed of traffic-related pollution, and particulate matter (PM) from urban agglomeration in Warsaw, Poland were investigated. Several magnetic methods, namely magnetic susceptibility, thermomagnetic curves, hysteresis loops, decomposition of isothermal remanent magnetization acquisition curves, and first-order reversal curves, were performed to evaluate the magnetic fraction of dust. Magnetite was the main magnetic phase in all types of samples, with a small amount of high-coercive hematite within ironworks and street dust samples. Significant differences were observed in the domain structure (grain size) of industrial and traffic-related magnetic particles. The grain size of TMP obtained from steel production was in the range of 5–20 µm and was predominated by a mixture of single-domain (SD) and multidomain (MD) grains, with the prevalence of SD grains in the topsoil affected by Třinec ironwork. The traffic-related dust contained finer grains with a size of about 0.1 µm, which is characteristic of the pseudo-single-domain (PSD)/SD threshold. Street dusts were composed of a slightly higher proportion of MD grains, while PM also revealed the typical behavior of superparamagnetic particles.

Noncollinear states in a chain of single-domain magnetic particles

JETP Letters ◽  
2011 ◽  
Vol 93 (12) ◽  
pp. 716-719 ◽  
Author(s):  
K. P. Mukhamatchin ◽  
A. A. Fraerman
Keyword(s):  
Magnetic Particles ◽  
Single Domain ◽  
A Chain

A pseudo-single domain theory of paleomagnetic recording

2020 ◽  
Author(s):  
Karl Fabian ◽  
Lennart V. de Groot
Keyword(s):  
Magnetic Particles ◽  
Small Sample ◽  
Single Domain ◽  
Measured Signal ◽  
Statistical Interpretation ◽  
Practical Applications ◽  
Physical Description ◽  
Statistical Sample ◽  
Small Sample Sizes ◽  
Physical Consequences

<p>The common theory of paleomagnetic recording is based on the acquisition of thermoremanent magnetization in  single-domain (SD) particles (Neel, 1955). The physical consequences of this theory  agree  well enough  with observations as to be of utmost use in understanding and assessing the quality of paleomagnetic data in almost all practical applications in paleomagnetism. This is to a large extent due to the statistical nature of the interpretations based on SD theory, which apparently is sufficiently robust to make up for minor descrepancies between the real remanence carriers and their physical description on which the statistical interpretation is founded. Exceptions to this rule are becoming more important as increasingly sophisticated technical methods for paleomagnetic measurements are developed and used, that involve fewer and fewer individual magnetic particles to contribute to the measured signal. Examples are the determination of paleointensity from individual mineral grains, and the development of scanning magnetometers that average over relatively small numbers of magnetic grains in a sample. The statistical uncertainties of paleomagnetic quantities resulting from using small sample sizes have been studied for SD particle ensembles for example by Berndt et al. (2016).  First experimental data indicate that in case of PSD particles the statistical sample size required to  reconstruct paleomagnetic field direction may be smaller than for SD particles. Here, a theoretical study is presented that describes the micromagnetic background of this hypothesis and allows to test  it for a simplified mathematical model of TRM acquisition in PSD particles.</p>

Sign in / Sign up

Export Citation Format

Share Document