Ориентационная зависимость магнитного момента микропроводов alpha-Fe(PrDy)(CoFeB)

The anisotropy of magnetization of α-Fe/(PrDy)(FeCo) core-shell microwires was studied at 300 K. The magnetization component of the α-Fe core directed along microwire axis and non-collinearly directed component of the microwire shell with correspondent saturation fields~ 100 Oe and > 10 kOe were separated. The directions of magnetizations of the shell and core of the microwire are differ by 170 grad.

Deformation of rhyolite lava crust associated with intermittent inner flow of lava: palaeomagnetic evidence

SUMMARY A palaeomagnetic study has been conducted to examine the deformation of thick crusts of rhyolite lava while its inner portions continue to flow. The Sanukayama rhyolite lava, which erupted in the Pleistocene in Kozushima Island, Japan, was chosen as the investigation site because of its well-exposed vertical lithofacies variations classified into three distinct zones (pumiceous, obsidian and crystalline). The targets of this study are the pumiceous and obsidian zones, which constitute the crust of the lava. Thermal demagnetization reveals three remanent magnetization components from the pumiceous and obsidian samples but only a single magnetization component from the inner crystalline rhyolite samples. Alternating field demagnetization is ineffective in isolating the magnetization components in the pumiceous and obsidian samples. The multiple components of remanent magnetization of the crust are interpreted to have been acquired during cooling as thermoremanent magnetizations. We suspect intermittent lava transport of the inner portions, the primary mode of rhyolite lava advancement, to be responsible for the presence of multiple components in pumice and obsidian of the lava crust. When the inner portions of the lava retain mobility to flow out of the crust, the solidified crust of the lava surface below the magnetite Curie temperature remains susceptible to deformation. Analysis of palaeomagnetic directions from the crust allows the deformation of the crust to be described in terms of rotation. Although the mode of rhyolite lava advancement is not well understood, because of its infrequent occurrence, our observations offer an important insight on how the mobile part of the lava is associated with the deformation of the crust during continued lava advance.

Paleomagnetic studies sariolyiski conglomerates of the Onega structure of the Karelian craton: Paleoproterozoic global remagnetization

As a result of paleomagnetic studies Sariolian 2,4–2,3 Ga conglomerates of the Onega basin of the Karelian protoctaton, two characteristic components of magnetization have been separated. Mean direction of the medium-temperature component has a heap distribution and coincides with mean direction of the Svecofennian remagnetization within the Karelian protocraton. The directions of high-temperature magnetization components isolated in conglomerates have a significant spread, which indicates the primary nature of this magnetization component. Two clusters of high-temperature components associated not only with the composition of protolites, but also with different conditions of rock transformations, including their fluid saturation, are distinguished.

The Magnetization Reversal Processes Of Bulk (Nd, Y)-(Fe, Co)-B Alloy In The As-Quenched State

The magnetization reversal processes of bulk Fe64Co5Nd6Y6B19 alloy in the as-quenched state have been investigated. From the analysis of the initial magnetization curve and differential susceptibility versus an internal magnetic field it was deduced, that the main mechanism of magnetization reversal process is the pinning of domain walls at the grain’s boundaries of the Nd2Fe14B phase. Basing on the dependence of the reversible magnetization component as a function of magnetic field it was found that reversible rotation of a magnetic moment vector and motion of domain walls in multi-domain grains result in high initial values of the reversible component. The presence of at least two maxima on differential susceptibility of irreversible magnetization component in function of magnetic field imply existence of few pinning sites of domain walls in Fe64Co5Nd6Y6B19 alloy. The dominant interactions between particles have been determined on the basis of the Wohlfarth dependence. Such a behavior of Wohlfarth’s plot implies that the dominant interaction between grains becomes short range exchange interactions.

Remagnetization of Upper Jurassic limestones from the Danubian Unit (Southern Carpathians, Romania): tectonic implications

We present a pioneering paleomagnetic study on Upper Jurassic limestones from the Danubian Unit (Southern Carpathians, Romania). Thermal and alternating field demagnetizations were applied to define the characteristic remanent magnetization component in all six localities (81 samples). All samples have a normal polarity characteristic remanent magnetization. Negative regional and local fold tests suggest that this remanent magnetization is in fact a remagnetization produced by late diagenetic processes. The studied limestones were probably remagnetized during the collision of the Getic Unit and Danubian Unit which took place during the long normal polarity Chron C34 (82-118 Ma). The area mean direction (D = 75.5°, I = 50.0°, α95 = 10.2°, k = 44) implies about 75° clockwise rotation post remagnetization. Our paleomagnetic results further indicate the absence of significant relative rotation between the Getic Unit and the Danubian Unit during the Cenozoic.