Axis, easy

Let the interface be in the xy-plane, as shown in Fig.lO. 15. The equilibrium position of the director n (the so-called easy direction or easy axis) is defined by the zenithal (Sq) and azymuthal ( )o) angles counted from the z and x axes, respectively. At the free surface of the nematic the easy direction appears spontaneously but at the nematic-solid interface it is predetermined by a specific treatment of the solid surface. We can distinguish the homeotropic (9q = 0), planar (9q = nj2) and tilted 

Surface free energy of the nematic phase 4 )is minimal for the easy 

In order to consider any mechanical or electro-optical effects for a liquid crystal layer placed between two solid substrates one must solve a problem of the distribution of the director over the layer with allowance for the boundary conditions. The standard variational procedure allows such calculations when the surface energy depends only on orientation of the director (angles 9 and 4 ) at both boundaries but not on their spatial derivatives. 

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Fig. 11. Magnetization M in the direction of the appHed field H for various appHed-field angles with the easy axis (33).

At a field at which the particle is saturated perpendicular to the easy axis (oc = 90), = 2Kj. This field can be defined as the anisotropy... 

If there is a crystal anisotropy, with the easy axis parallel to the shape-anisotropy axis of the particle, the total anisotropy is = shape + crystal and the total switchHig field is = (A — Aj,)Af + 2Aj = crystal anisotropy constant). In the case of practical... 

Magnetic Anisotropy Energy. There are several kinds of magnetic anisotropy energy and perhaps the most weU known is the magnetocrystaUine anisotropy. Only a crystalline soHd has this property because the energy is dictated by the symmetry of the crystal lattice. For example, in bcc Fe, the easy axis is in a (100) direction and in fee Ni, it is in a (111) direction. 

As the appHed field is reduced, the iaductioa does aot retrace curve 1 but foUows curve 2 as the domaias at first merely rotate back to the aearest local easy axis directioa. The value of B at i/ = 0 is the remanent iaductioa. At H = which is the coercive-field strength of coercive force or... 

In a polycrystalline film, the easy axis can vary from point to point about an average direction. This dispersion is represented by a dispersion angle, a, which is the dispersion of easy axes about the average direction. A film quaUty factor q, where q = used as a measure of the usefiilness of a... 

Co—Fe/Cu grew having inplane uniaxial aniso-tropy and easy axis parallel to the cube direction in the MgO(llO) plane satu-ration field (240 kA/m) at room temperature for... 

The fluctuations of the magnetization direction around an easy axis, known as collective magnetic excitations, can be considered fast compared to the time scale of Mossbauer spectroscopy because there are no energy barriers between magnetization directions close to an easy direction, and the magnetic splitting in the... 

The value is derived from a zero-field spectrum recorded at 150 K. A q could not be determined at 4.2 K because the compound is in the limit of slow paramagnetic relaxation and the strong unquenched orbital moment forces the internal field into the direction of an easy axis of magnetization. As a consequence, the quadrupole shift observed in the magnetically split spectra results only from the component of the EFG along the internal field and the orientation of the EFG is not readily known dbabh is a bulky N-coordinating amide... 

The structures of electroplated hard alloys have been less extensively studied than those of similar electrolessly deposited materials. Sallo and co-workers [118-120] have investigated the relationship between the structure and the magnetic properties of CoP and CoNiP electrodeposits. The structures and domain patterns were different for deposits with different ranges of coercivity. The lower-f/c materials formed lamellar structures with the easy axis of magnetization in the plane of the film. The high-Hc deposits, on the other hand, had a rod-like structure, and shape anisotropy may have contributed to the high coercivity. The platelets and rods are presumed to be isolated by a thin layer of a nonmagnetic material. 

Rotating single-crystal measurements also permitted the extraction of the orientation of the magnetic tensor in the molecular reference frame and the experimental easy axis was found to coincide with the idealized tetragonal axis of the coordination dodecahedron of Dy. Crystal field calculations assuming idealized tetragonal symmetry permitted the reproduction of magnetic susceptibility data for gz = 19.9 and gxy 0 [121]. More elaborated calculations such as ab initio post Hartree-Fock CASSCF confirmed this simple analysis [119]. 

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