Anomalous Domain Research Articles

A teleseismic and petrological study of the crust and upper mantle beneath the geothermal anomaly Urach/SW-Germany

Teleseismic P-wave travel time residuals recorded by a mobile, shortperiod network are interpreted using the composition of crustal and upper mantle xenoliths. A three-dimensional inversion of the P residuals revealed a small-scale anomalous domain with a velocity reduction of 3% in the crust and a broad low-velocity anomaly of 4% beneath the Moho down to a depth of 50 km. Xenoliths of the Miocene Urach volcanic field (“UVF”, 1300 km 2; 355 eruptive centres, mostly diatremes) comprise phlogopite-bearing, clinopyroxene-rich mantle xenoliths, evidence for large ion lithophile element (LIL) metasomatism in an originally depleted harzburgitic mantle, reflecting chemical modification of the upper mantle beneath the UVF. The metasomatism caused partial melting in the spinel peridotite stability field, indicated by glasses in xenoliths, and a diapiric uprise of the partially molten metasomatized mantle. The observed reduction of the P-wave velocity of 4% in the lithospheric mantle can be explained by a local enrichment of phlogopite accompanied by increased temperatures. The crustal low-velocity body coincides very well with the postulated volume of an ancient intracrustal magma chamber or system of chambers required by the composition of xenoliths, the magnetization of the diatremes and the spatial distribution of the volcanic eruption centres.

Relaxations of surface pressure in octadecanol monolayers

Relaxations of surface pressure with time have been observed in octadecanol monolayers. These relaxations occur at low surface pressure and in the “incompressible” phase above the breakpoint. The anomalous domain of temperature of fatty alcohols is characterized by a different aspect of these relaxations. An alternative phase diagram is proposed for the true equilibrium isotherms recorded.

Bimodal electromagnetic induction in non-uniform thin sheets with an application to the northern Pyrenean induction anomaly

In order to handle the distortion of large-scale induced electric currents by local conductivity anomalies, the problem of electromagnetic induction in non-uniform thin sheets has been reformulated in terms of an integral equation over the anomalous domain. This formulation considers in the layered substratum in addition to toroidal currents also the poloidal current mode (vertical current loops), at the expense that two scalar functions have to be determined. Simple formulas for the required kernels are derived. The algorithm is applied to model the gross features of the northern Pyrenean induction anomaly. It is suggested that this pronounced anomaly results from a conductive channel between the Atlantic Ocean and the Mediterranean Sea.

Anomalous hysteresis loops and domain observation in Gd-Fe Co-evaporated films

Magnetization process of the amorphous Gd-Fe films, which were prepared by the co-evaporation technique, has been studied microscopically by the magneto-optical Kerr effect. It has been found that these films show the anomalous hysteresis loops and the peculiar domain behavior. This anomaly has been explained consistently by the double layers model with the compensation wall inclined from the axis normal to the film plane.

Electron microscopic observation of ferroelectric and antiphase domains in Gd2(MoO4)3

Abstract The ferroelectric and antiphase domain structures of Gd2(MoO4)3 have been studied by means of electron microscopy. Anomalous right-angled ferroelectric domain walls in (001) films were observed and the lattice distortions around them were analysed by the use of the moire technique. The existence of antiphase boundaries due to the space group of the ferroelectric phase was proved in the dark-field images produced by the superlattice reflections.

Anomalous Alignment and Domains in a Nematic Liquid Crystal

The relationship between anomalous alignment and domain formation is examined for the room temperature nematic liquid crystal, p-methoxybenzilidene p-n-butylaniline (MBBA). An increase in order with the long molecular axes preferring a direction perpendicular to an externally applied low-frequency electric field is observed for potential differences below the threshold voltage for anomalous alignment. Employing measurements of the dielectric loss at a microwave frequency of 24.4 GHz, the threshold voltage for anomalous alignment is examined as a function of the frequency of an externally applied electric field. This is then contrasted with the frequency dependence of the threshold voltage for domain formation as determined from visual observation. Comparing optical and dielectric data we show that the threshold is the same in each case. At very high electric field strengths, behavior indicating a tendency towards random molecular alignment is observed.

Domain configurations in laminated thin magnetic films

Domain configurations in laminated magnetic film elements comprising two equal thickness layers of Permalloy separated by silicon monoxide are described. Individual layer thicknesses were in the range 15 to 200 nm. Elements with NiFe layers less than 100 nm thick show line domains and a locked domain structure on easy-axis field switching. These effects are attributed to magnetostatic effects between the laminations, as is the extended range of film thicknesses exhibiting Néel-type walls. In the range 90- to 200-nm NiFe thickness, anomalous domain propagation takes place, possibly the result of ordered growth of the upper magnetic layer.

Thin permalloy films: optimization of properties for computer memories

The vacuum deposition of Ni-Fe elements on glass for use in a 6000 bit, 100 ns cycle time memory is described. Measurement of the magnetic properties of some 20 000 elements has enabled reliable correlation to be made with film composition and deposition conditions.Memory testing of elements made with calculated optimum dimensions show that films 100 nm thick have wide operating limits because of high coercivity and freedom from cross-tie walls.Tapering the ends of the elements increased the domain nucleation coercivity above the wall coercivity. Although producing films with rectangular hysteresis loops, tapering did not increase the creep disturbance threshold.Films thicker than 180 nm show anomalous domain configurations in hard direction fields together with a steep rise in wall coercivity and increased dispersion.