Field-induced ordering

In the materials RbFeClj and CsFeCl3 the Fe ions form chains that lie along the crystal c axis. The distance between Fe ions within the chain is less than half the separation between chains. In RbFeClj, for temperatures below the Neel temperature of 2.55 K, the Fe spins are coupled ferromagnetically (i.e. parallel to each other) within the chains and antiferromagnetically (i.e. antiparallel to each other) between chains. In CsFeCls no ordering has been observed down to the lowest temperatures investigated (80 mK). 

3 K spectrum of the ordered phase is characteristic of a weak hyperfine field, which is perpendicular to the axis of the dominant electric quadrupole interaction. 

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Various types of work in addition to pV work are frequently involved in experimental studies. Research on chemical equilibria for example may involve surfaces or phases at different electric or magnetic potentials [11], We will here look briefly at field-induced transitions, a topic of considerable interest in materials science. Examples are stress-induced formation of piezoelectric phases, electric polarization-induced formation of dielectrica and field-induced order-disorder transitions, such as for environmentally friendly magnetic refrigeration. 

EO response can be introduced into polymers containing the donor-conjugation-acceptor moieties by applying a very strong electric field while the polymer is heated to its Tg. The field-induced order is subsequently frozen in by cooling the polymer films well below Tg. The achievable second-order susceptibility... 

Ram, P., and J.H. Prestegard (1988) Magnetic field induced ordering of bile salt/phospholipid micelles new media for NMR structural investigations. Biochim. Biophys. Acta 940, 289-294. 

Firestone MA, Seifert S, Tiede DM. 2000. Magnetic field-induced ordering of a polymer-grafted biomembrane-mimetic hydrogel. J Phys Chem B 704 2433-2438. 

L and dependence on temperature and film thickness in Fig. 3.24. It follows from Fig. 3.24a, c, that at fixed temperature the average polarization L decreases for the film thinning (compare curves 1-5). Built-in field smears the temperature of phase transition and susceptibility maximum its influence increases with the films thinning (see Fig. 3.24b, d). Moreover, the order parameter behavior for the thinnest possible films resembles that for thin films of ordered ferroelectrics with the thickness less than critical one (compare the curves 5 in Fig. 3.24c, d with Fig. in the paper [54]). Built-in field induces order parameter in the film with maximal disorder, see dotted curves 5 in Fig. 3.24a, b. However hysteresis loops is absent on these curves so that the behavior resembles that of electret state. 

Fig. 63. Left panel Complete B-T phase diagram (Maple et al., 2002) with SC regime and region of field induced order parameter which is presumably of antiferroquadrupolar (AFQ) type. Data are obtained from resistivity (p), magnetization (M), specific heat (C) and thermal expansion (o ) measurements. Right panel High magnetic field phase diagram (Aoki et al., 2003) with upper part of AFQ phase (full squares) and line of high field Schottky anomaly from the Fi-Fs crossing. The inset shows calculation for tetrahedral CEF model.

The field-induced order can be related to the Kerr constant B = An Q E)/XE, ... 

The first observation of optical-field induced ordering in the isotropic phase of a nematic liquid crystal was reported by Wong and Shen [74]. They have used a linearly polarized Q-switched, 50 kW ruby laser pulse to induce molecular ordering in the isotropic phase of a nematic liquid crystal. The in-... 

The even-order terms represent the zero-field order and the odd-order terms the field induced order. Also... 

There are mote dye molecules oriented along the optical field inducing order... 

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