Magnetic Susceptibilities of Paramagnetic and Diamagnetic Materials at 20°C

Material
cm=Km-1
(x 10-5)
Paramagnetic
Iron aluminum alum
66
Uranium
40
Platinum
26
Aluminum
2.2
Sodium
0.72
Oxygen gas
0.19
Diamagnetic
Bismuth
-16.6
Mercury
-2.9
Silver
-2.6
Carbon (diamond)
-2.1
Lead
-1.8
Sodium chloride
-1.4
Copper
-1.0
ParamagnetismDiamagnetism
Here the quantity Km is called the relative permeability, a quantity which measures the ratio of the internal magnetization to the applied magnetic field. If the material does not respond to the magnetic field by magnetizing, then the field in the material will be just the applied field and the relative permeability Km =1. A positive relative permeability greater than 1 implies that the material magnetizes in response to the applied magnetic field. The quantity cm is called magnetic susceptibility, and it is just the permeability minus 1. The magnetic susceptibility is then zero if the material does not respond with any magnetization. So both quantities give the same information, and both are dimensionless quantities.

For ordinary solids and liquids at room temperature, the relative permeability Km is typically in the range 1.00001 to 1.003. We recognize this weak magnetic character of common materials by the saying "they are not magnetic", which recognizes their great contrast to the magnetic response of ferromagnetic materials. More precisely, they are either paramagnetic or diamagnetic, but that represents a very small magnetic response compared to ferromagnets.

Index

Tables

Reference
Young
Section 29-8
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Magnetic Properties of Ferromagnetic Materials

Material
Treatment
Initial Relative
Permeability
Maximum Relative
Permeability
Coercive
Force
Remanent Flux
Density
Iron, 99.8% pure
Annealed
150
5000
1.0
13,000
Iron, 99.95% pure
Annealed in hydrogen
10,000
200,000
0.05
13,000
78 Permalloy
Annealed, quenched
8,000
100,000
.05
7,000
Superpermalloy
Annealed in hydrogen, controlled cooling
100,000
1,000,000
0.002
7,000
Cobalt, 99% pure
Annealed
70
250
10
5,000
Nickel, 99% pure
Annealed
110
600
0.7
4,000
Steel, 0.9% C
Quenched
50
100
70
10,300
Steel, 30% Co
Quenched
...
...
240
9,500
Alnico 5
Cooled in magnetic field
4
...
575
12,500
Silmanal
Baked
...
...
6,000
550
Iron, fine powder
Pressed
...
...
470
6,000
Discussion of relative permeability
Index

Tables

Reference
Brown
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