Diamagnetic

Pyrolytic carbon hovering over a neodymium magnet .

Diamagnetics are atoms magnetized against the direction of an external magnetic field . In the presence of an internal magnetic field, diamagnetics are magnetic. Under the influence of an external magnetic field, each substance of a diamagnet acquires a magnetic susceptibility I (and each unit of volume, the magnetization M), proportional to the magnetic induction B and directed towards the field. Therefore, magnetic susceptibility $\chi$ ${\ displaystyle \ chi}$ $\ chi$ = M / H for diamagnetic is always negative. Absolute magnitude diamagnetic susceptibility $\chi$ ${\ displaystyle \ chi}$ $\ chi$ is small and highly dependent on both the magnetic field strength and temperature .

In other words, magnetic permeability $\mu \lesssim 1$ ${\ displaystyle \ mu \ lesssim 1}$ $\ mu \ lesssim 1$ and weakly depends on the strength of the magnetic field, and on temperature .

Content

History

In 1778, C. J. Bergman became the first person to notice that bismuth and antimony are repelled by a magnetic field. However, the term “ diamagnetism ” was introduced later (in September 1848) by Michael Faraday , when he realized that all materials in nature possess a somewhat diamagnetic character of the response to a magnetic field applied to them.

Substances - Diamagnetics

Magnetic susceptibility of some diamagnetic (under normal conditions)
Substance	Magnetic susceptibility ^[1] , $\chi$ ${\ displaystyle \ chi}$ · 10 ^-6
Nitrogen , N ₂	−3.0
Hydrogen , H ₂	−4.0
Germanium , Ge	−12,7
Silicon , Si	−3,1
Water (liquid), H ₂ O	−13,0,0
Cooking salt , NaCI	−30,3
Acetone , C ₃ H ₆ O	−33,8
Glycerin , C ₃ H ₈ O ₃	−57,1
Naphthalene , С ₁₀ Н ₈	−91,8
Bismuth , Bi, metal	−284.0
Pyrolytic graphite , P, C	−85
Pyrolytic graphite , ⊥, С	−950

Diamagnetic materials include inert gases , nitrogen , hydrogen , silicon , phosphorus , bismuth , zinc , copper , gold , silver , as well as many others, both organic and inorganic, compounds. A person in a magnetic field behaves like a diamagnetic.

Diamagnetic Levitation

A living frog levitates in a magnetic field ~ 16 Tesla ( NHFML ) Watch a video .

Diamagnetic levitation is of the same nature as the Meissner effect (complete extrusion of the magnetic field from the material), it is observed at much stronger fields, but it does not require pre-cooling. Some experiences are available to lovers. For example, a rare-earth magnet with an induction of about 1 T may hang between two bismuth plates ^[2] ^[3] ^[4] . In a field with an induction of 11 T, it is possible to stabilize and hold a small magnet in the air between the fingers without touching it ^[5] .

Notes

↑ See some of the meanings in the TSB article table.
↑ Experiments on magnetic levitation (Finnish)
↑ avi-video recording of "levitation" of a magnet between two bismuth blocks
↑ MPEG-1 video recording of a levitation magnet between two bismuth blocks
↑ Diamagnetically stabilized magnet levitation
↑ Tolstoy N. A., Spartak A. A. New type of magnetism - aromagnetism // Letters to JETP, vol. 52, no. 3, s. 796-799

Links

Diamagnetic - an article from the Great Soviet Encyclopedia
Heard KM - Variety of types of magnetic ordering in solids
Diamagnetically stabilized magnet levitation
Video demonstration of the properties of diamagnetic
Diamagnetic properties

[1] See some of the meanings in the TSB article table.

[2] Experiments on magnetic levitation (Finnish)

[3] vi-video recording of "levitation" of a magnet between two bismuth blocks

[4] MPEG-1 video recording of a levitation magnet between two bismuth blocks

[5] Diamagnetically stabilized magnet levitation

[6] Tolstoy N. A., Spartak A. A. New type of magnetism - aromagnetism // Letters to JETP, vol. 52, no. 3, s. 796-799