Deformation magnetic effects

In effect of loads acting in the scope of elastic deformations (proportional) in polycristalline bodies, changes in distances between atomic surfaces of the net are observed, which change the initial magnetic permeability. 

Watkins and Pound (104) performed an experiment which illustrates the effect of strain on the magnetic resonance of bromine and iodine nuclei in cubic KBr and KI. These crystals were subjected to plastic deformation (a 22% change in dimension occurred along the 100 axis for the KI crystal) and it was found that the intensity of the resonance line in the original undeformed crystals decreased to 0.4 of its original value for the bromine isotopes (Br , Br , I = and to 0.3 of its original value for the I (I = resonance. 

The title of the book, Optical Rheometry of Complex Fluids, refers to the strong connection of the experimental methods that are presented to the field of rheology. Rheology refers to the study of deformation and orientation as a result of fluid flow, and one principal aim of this discipline is the development of constitutive equations that relate the macroscopic stress and velocity gradient tensors. A successful constitutive equation, however, will recognize the particular microstructure of a complex fluid, and it is here that optical methods have proven to be very important. The emphasis in this book is on the use of in situ measurements where the dynamics and structure are measured in the presence of an external field. In this manner, the connection between the microstructural response and macroscopic observables, such as stress and fluid motion can be effectively established. Although many of the examples used in the book involve the application of flow, the use of these techniques is appropriate whenever an external field is applied. For that reason, examples are also included for the case of electric and magnetic fields. 

In the spin deformation density the first-order overlap effect is dependent on Y + S, rather than onY-S. It is therefore more pronounced than in the case of the charge density. It follows that a molecular orbital formalism is most likely to be productive if applied to a combination of X-ray data on the charge density and polarized neutron data on the magnetization density. 

The magnetostrictive measurements were made on the same Ni plate. In the external magnetic fields more than 100 mT the change of deformations were not essential. However, the GMR effect appeared as usual in such fields. There was not any correlation between the magnetostrictive deformation and the stepwise change of current of the Ni-polymer-Cu structure. 

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