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There are two classes of materials for which this holds: Molecular materials with a (isolated) paramagnetic center. Good examples are coordination complexes of d- or f-metals or proteins with such centers, e.g. myoglobin. In such materials the organic part of the molecule acts as an envelope shielding the spins from their neighbors.
There are two types of interaction. Diamagnetism. When placed in a magnetic field the atom becomes magnetically polarized, that is, it develops an induced magnetic moment. The force of the interaction tends to push the atom out of the magnetic field. By convention diamagnetic susceptibility is given a negative sign.
Magnetic susceptibility indicates whether a material is attracted into or repelled out of a magnetic field. Paramagnetic materials align with the applied field and are attracted to regions of greater magnetic field. Diamagnetic materials are anti-aligned and are pushed away, toward regions of lower magnetic fields.
The Euler relation for a paramagnetic system is then: = + + and the Gibbs-Duhem relation for such a system is: S d T − V d P + I d B e + N d μ = 0 {\displaystyle SdT-VdP+IdB_{e}+Nd\mu =0} An experimental problem that distinguishes magnetic systems from other thermodynamical systems is that the magnetic moment can't be constrained.
Two linearly polarized fields are generated by rf currents in two wires which are oriented parallel to the magnetic field. The wires are then connected into half loops which then cross at a 90 degree angle. This technique was developed by Schweiger and Gunthard so that the density of ENDOR lines in a paramagnetic spectrum could be simplified. [11]
The appropriate two-band effective Hamiltonian is + = + where is the 2 × 2 identity matrix, , the Pauli matrices and the electron effective mass. The spin–orbit part of the Hamiltonian, H R {\displaystyle H_{\text{R}}} is parametrized by α {\displaystyle \alpha } , sometimes called the Rashba parameter (its definition somewhat varies ...
Heated to temperatures above T C, ferromagnetic materials become paramagnetic and their magnetic behavior is dominated by spin waves or magnons, which are boson collective excitations with energies in the meV range.
Here two extreme points of view can be contrasted: in the Stoner picture of magnetism (also called itinerant magnetism), the electronic states are delocalized, and their mean-field interaction leads to the symmetry breaking. In this view, with increasing temperature the local magnetization would thus decrease homogeneously, as single ...