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In classical electromagnetism, magnetization is the vector field that expresses the density of permanent or induced magnetic dipole moments in a magnetic material. Accordingly, physicists and engineers usually define magnetization as the quantity of magnetic moment per unit volume. [1]
In conventional NMR spectroscopy, T 1 limits the pulse repetition rate and affects the overall time an NMR spectrum can be acquired. Values of T 1 range from milliseconds to several seconds, depending on the size of the molecule, the viscosity of the solution, the temperature of the sample, and the possible presence of paramagnetic species (e.g ...
Seen in some magnetic materials, saturation is the state reached when an increase in applied external magnetic field H cannot increase the magnetization of the material further, so the total magnetic flux density B more or less levels off. (Though, magnetization continues to increase very slowly with the field due to paramagnetism.)
It is the ratio of magnetization M (magnetic moment per unit volume) to the applied magnetic field intensity H. This allows a simple classification, into two categories, of most materials' responses to an applied magnetic field: an alignment with the magnetic field, χ > 0 , called paramagnetism , or an alignment against the field, χ < 0 ...
This effect is expressed on a macroscopic scale in the Einstein–de Haas effect, or "rotation by magnetization", and its inverse, the Barnett effect, or "magnetization by rotation". [1] Further, a torque applied to a relatively isolated magnetic dipole such as an atomic nucleus can cause it to precess (rotate about the axis of the applied field).
Crucially, the Larmor frequency is independent of the polar angle between the applied magnetic field and the magnetic moment direction. This is what makes it a key concept in fields such as nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR), since the precession rate does not depend on the spatial orientation of the spins.
The magnetization is the negative derivative of the free energy with respect to the applied field, and so the magnetization per unit volume is = , where n is the number density of magnetic moments. [1]: 117 The formula above is known as the Langevin paramagnetic equation.
where , the magnetization, is the order parameter, is the applied magnetic field, is the critical temperature, and , are material constants. Close to the phase transition, this gives a relation for the magnetization order parameter: