Does centre of symmetry has something to do with magnetic dipole interaction. As in the case electric interaction the centre of symmetry kills the chi 2 process ??
may be ,,,but I need full description about my question sir..............
I'm trying to make a qualitative explanation:
In magnetic material, there are spin polarizations, for electrons or nucleis.
The spin is a vector, which have different directions, and obey pauli's exclusion principle.
These properties break the spatial asymmetry.
Magetism is due to the spin rotation of electronic charge, and it is odd considering that
it will change with time.
Hysteresis effects by definition break time reversal symmetry on a macroscopic scale. Although time reversal symmetry is usually not broken on a subatomic scale length, time reversal can be broken on a macroscopic scale by hysteresis effects or by friction. Ferromagnetic materials usually have hysteresis curves. One can calculate the amount of entropy created in one cycle of a hysteresis curve.
Spatial inversion can also be broken on a macroscopic scale. If a ferromagnetic material is magnetized, the material gains a magnetic dipole. The magnetic dipole breaks inversion symmetry in the material. However, spatial inversion in this case is not broken on a subatomic scale.
Consider a charged particle moving in a homogeneous magnetic field. It is subject to the Lorentz Force. In the absence of other forces (and neglecting radiation losses) it will move with constant velocity on a circular trajetory.
At any given moment in time, flip the velocity vector to its negative and see what happens to the motion. Flipping the velocity to its negative is equivalent to "letting time flow backwards". You will find that the motion is still circulat, but its not the same circle. The trajectory is different under time reversal: "time reversal symmetry is broken".
Mathematically, this can be traced back to the vector product in the formulation of the Lorentz force.
Consider the operation of Faraday-effect magneto-optical isolators that prevent laser light back-reflections from re-entering laser cavities: "time reversal" is equivalent here to the light wave going backwards, during which, importantly, the polarisation plane of light is still being rotated in the same direction as initially. 90 degs. of rotation angle is achieved on traversing the magnetized medium on the way back and only 45 degs of one-way Faraday rotation is used. Without breaking time reversal symmetry, no isolators of this type would be possible.
Does centre of symmetry has something to do with magnetic dipole interaction. As in the case electric interaction the centre of symmetry kills the chi 2 process ??
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