Keely Net Mail List: Physics book types of magnetism

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In reference to the previous posts on north/south pole magnetism, I =
looked up the following definitions in my college physics text:

Ferromagnetism - For five elements (Fe, Co, Ni, Gd, and Dy) and for many =
alloys of these and other elements a special effect occurs which permits =
a specimen to achieve a high degree of magnetic alignment in spite of =
the randomizing tendency of the thermal motions of the atoms. In such =
materials, described as ferromagnetic, a special form of interaction =
called exchange coupling occurs between adjacent atoms, coupling their =
magnetic moments together in rigid parallelism. This is a purely quantum =
effect and cannot be explained in terms of classical physics. Modern =
quantum physics successfully predicts that this will occur only for the =
five elements listed. If the temperature is raised above a certain =
critical value, called the Curie temperature, the exchange coupling =
suddenly disappears and the materials become simply paramagnetic. For =
iron the Curie temperature is 1043 deg K. Ferromagnetism is evidently a =
property not only of the individual atom or ion but also of the =
interaction of each atom or ion with its neighbors in the crystal =
lattice of the solid.

Paramagnetism - Magnetism as we know it in our daily experience is an =
important but special branch of the subject called ferromagnetism. Here =
we discuss a weaker form of magnetism called paramagnetism. For most =
atoms and ions, the magnetic effects of the electrons, including both =
their spins and orbital motions, exactly cancel so that the atom or ion =
is not magnetic. This is true for the rare gases such as neon and for =
the ions such as Cu+, which makes up ordinary copper. These materials do =
not exhibit paramagnetism. For other atoms or ions the magnetic effects =
of the electrons do not cancel, so that the atom as a whole has a =
magnetic dipole moment u. Examples are found among the so-called =
transition elements, such as Mn++, the rare earths, such as Gd++, and =
the actinide elements, such as U++++.

Diamagnetism - The magnetic equivalent of induced electric dipole =
moments results in dimagnetism. It is present in all substances, but it =
is such a feeble effect that its presence is masked in substance made of =
atoms that have a permanent fixed magnetic dipole moment, that is, in =
paramagnetic or ferromagnetic substances. Dimagnetic materials also =
differ from paramagnetic and ferromagnetic materials (and also =
dielectric materials) in that the atomic dipoles are aligned in a =
direction opposite to that of the external field. Such materials are =
thus repelled from the pole of a strong magnet, whereas paramagnetic and =
ferromagnetic materials would be attracted under similar circumstances.

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Ferromagnetism - For five =elements (Fe,=20Co, Ni, Gd, and Dy) and for many alloys of these and other elements a =special=20effect occurs which permits a specimen to achieve a high degree of =magnetic=20alignment in spite of the randomizing tendency of the thermal motions of =the=20atoms. In such materials, described as ferromagnetic, a special form of=20interaction called exchange coupling occurs between adjacent atoms, =coupling=20their magnetic moments together in rigid parallelism. This is a purely =quantum=20effect and cannot be explained in terms of classical physics. Modern =quantum=20physics successfully predicts that this will occur only for the five =elements=20listed. If the temperature is raised above a certain critical value, =called the=20Curie temperature, the exchange coupling suddenly disappears and the =materials=20become simply paramagnetic. For iron the Curie temperature is 1043 deg =K.=20Ferromagnetism is evidently a property not only of the individual atom =or ion=20but also of the interaction of each atom or ion with its neighbors in =the=20crystal lattice of the solid.

Paramagnetism - Magnetism =as we know it=20in our daily experience is an important but special branch of the =subject called=20ferromagnetism. Here we discuss a weaker form of magnetism called =paramagnetism.=20For most atoms and ions, the magnetic effects of the electrons, =including both=20their spins and orbital motions, exactly cancel so that the atom or ion =is not=20magnetic. This is true for the rare gases such as neon and for the ions =such as=20Cu+, which makes up ordinary copper. These materials do not exhibit=20paramagnetism. For other atoms or ions the magnetic effects of the =electrons do=20not cancel, so that the atom as a whole has a magnetic dipole moment u. =Examples=20are found among the so-called transition elements, such as Mn++, the =rare=20earths, such as Gd++, and the actinide elements, such as =U++++.

Diamagnetism - The =magnetic equivalent=20of induced electric dipole moments results in dimagnetism. It is present =in all=20substances, but it is such a feeble effect that its presence is masked =in=20substance made of atoms that have a permanent fixed magnetic dipole =moment, that=20is, in paramagnetic or ferromagnetic substances. Dimagnetic materials =also=20differ from paramagnetic and ferromagnetic materials (and also =dielectric=20materials) in that the atomic dipoles are aligned in a direction =opposite to=20that of the external field. Such materials are thus repelled from the =pole of a=20strong magnet, whereas paramagnetic and ferromagnetic materials would be =attracted under similar circumstances.