Uncompensated spins

X and -X axes is altered by adding an additional uncompensated spin-lock period (Davis and Bax, 1985). The bandwidth of the DB-1 sequence can be further improved if composite pulses (60° 300°) and (60°300° ) are applied when the phase of the spin lock is changed from +x to —x and from -X to +x, respectively, in order to align the magnetization with the respective effective spin-lock axes (sequence DB-2 Bax and Davis, 1986). 

In the antiferromagnetic coupling scheme, polyradical possesses aCUs and the spin sites connected in an alternating mode. Equal values of S are associated with each spin site. The key to attaining high-spin ground state is the uncompensated connectivity between the spin sites that leads to uncompensated spin canceling, such as in hyper-branched structure shown in Fig. 8. 

Note that M and H have the same units, but in contradistinction to H. which is generated by electric currents or permanent magnets outside the material (which is why it is sometimes referred to as the magnetizing field). M is generated from the uncompensated spins and angular momenta of... 

The intermetallic compounds MnAs, MnSb, and MnBi crystallize with a nickel arsenide-type structure, and they have many features in common regarding their structure and nature of physical properties. At room temperature, all these compounds are ferromagnetic. The Curie point of manganese arsenide is 45°C of MnSb and MnBi it is 314 and 360°C, respectively. Their ferromagnetism is due to the uncompensated spins of the 3d electron shells of the manganese atoms, located at the crystal lattice points with the coordinates 0, 0, 0 and 0, 0, i. 

A layer of uncompensated spins at the surface is responsible for the ferromagnetic interactions observed at low temperatures in normally antiferromagnetic oxides such as MnO, NiO, and CoO [44,45,805,806]. Evidence for such a behavior can be seen from Fig. 1.10. In this study, the blocking temperature was shown to increase with increase in size for NiO and show the opposite trend for MnO nanoparticles. Nanoparticles of ReOs also turn ferromagnetic, exhibiting hysteresis at low temperatures (see Fig. 4.26) [250]. The... 

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