Contrast between Diamagnetic, Paramagnetic and Ferromagnetic Materials

Classification of magnetic materials. Properties of Diamagnetic, Paramagnetic and Ferromagnetic materials, comparison etc.

1. Difference between Diamagnetic, Paramagnetic and
Ferromagnetic materials
Diamagnetic Paramagnetic Ferromagnetic
Diamagnetic substances
are feebly repelled by
the applied magnetic
eld.
Paramagnetic sub-
stances are feebly
attracted by the applied
magnetic eld.
Ferromagnetic sub-
stances are strongly
attracted by the applied
magnetic eld.
Ex. Antimony, Bis-
muth, Copper, Gold, Sil-
ver, Mercury, Quartz, Al-
cohol, Water, Air, Argon,
Hydrogenetc.
Ex. Aluminum,
Chromium, Alkali met-
als, Alkaline earth
metals, Platinum, Oxy-
gen, CuSO4, MnSO4etc.
Ex. Iron, Cobalt, Nickel,
Steel, Gadoliniumetc.
The magnetic lines of
forces of the applied
magnetic eld tend
avoid the diamagnetic
materialsi.e.do not
penetrate the material
The magnetic lines of
forces of the applied
magnetic eld tend pen-
etrate the paramagnetic
materials
The magnetic lines of
forces of the applied
magnetic eld tend to
strongly penetrate the
ferromagnetic materials
In a non-uniform mag-
netic eld, the diamag-
netic materials move
from stronger to weaker
eld due to repulsion
In a non-uniform mag-
netic eld, the param-
agnetic materials move
from weaker to stronger
eld with weak attrac-
tion
In a non-uniform mag-
netic eld, the fer-
romagnetic materials
move from weaker to
stronger eld with
strong attraction
When a diamagnetic rod
is freely suspended in a
uniform magnetic eld,
it slowly align itself in
a direction perpendicu-
lar to the applied mag-
netic eld.
When a paramagnetic
rod is freely suspended
in a uniform magnetic
eld, it slowly align it-
self parallel to the ap-
plied magnetic eld.
When a ferromagnetic
rod is freely suspended
in a uniform magnetic
eld, it quickly align it-
self parallel to the ap-
plied magnetic eld.
Contd..
1

2. No liquid is ferromag-
netic.
Applied magnetic eld
causes the diamagnetic
material to weakly mag-
netize in the direction
opposite to the applied
eld.
Applied magnetic eld
causes the paramag-
netic material to weakly
magnetize in the same
direction as the applied
eld.
Applied magnetic eld
causes the param-
agnetic material to
strongly magnetize in
the same direction as
the applied eld.
Diamagnetic materials
have net zero magnetic
dipole moments in them
in the absence of ap-
plied magnetic eld.
Paramagnetic mate-
rials have permanent
magnetic dipole mo-
ments in them ran-
domly oriented spin
magnetic moments, in
the absence of applied
magnetic eld.
Ferromagnetic materi-
als also have perma-
nent magnetic dipole
moments due to par-
allel aligned spin mag-
netic moments in the
form of domains, in the
absence of applied mag-
netic eld.
Diamagnetic materials
possess magnetic prop-
erties due to orbital mo-
tion(orbital angular mo-
mentum) of electrons.
Paramagnetic materi-
als possess permanent
magnetic properties
due to orbital angular
momentum and spin
angular momentum of
electrons.
Ferromagnetic materi-
als also possess perma-
nent magnetic proper-
ties due to formation of
spin domains.
The induced
magnetization(M) in
diamagnetic materials
is small and negative.
The induced
magnetization(M) in
paramagnetic materials
is small and positive.
The induced
magnetization(M) in
ferromagnetic materials
is large and positive
The magnetic perme-
abilityof diamagnetic
materials has a value,
less than unity.
The magnetic perme-
abilityof paramag-
netic materials has a
large value(greater than
unity).
The magnetic perme-
abilityof ferromag-
netic materials has a
very large value.
The relative permeabil-
ity of diamagnetic mate-
rialsr1.
The relative permeabil-
ity of paramagnetic ma-
terialsr>1.
The relative permeabil-
ity of ferromagnetic ma-
terialsr1.
Contd..
2

3. The susceptibility=
M
H
(magnetization pro-
duced per unit applied
magnetic eld inten-
sity) has negative value.
Susceptibilityhas low
positive value.
Susceptibilityhas
high positive value.
These materials do not
obey Curie law

/
1
T

,
the properties are inde-
pendent of temperature
These materials obey
Curie law

/
1
T

, their
properties change with
rise in temperature.
They obey Curie-Weiss
law

/
1
TTc

, they con-
vert to paramagnetic
at a temperature called
Curie temperature.
For diamagnetic materi-
als the MvsH curve and
the behavior of suscep-
tibility with respect to
temperature is as shown
below
For paramagnetic mate-
rials the MvsH curve
and the behavior of sus-
ceptibility with respect
to temperature is as
shown below
For ferromagnetic mate-
rials the MvsH give
rise to hysteresis curve
over a complete cy-
cle. The susceptibility
shows a transition from
ferromagnetic to para-
magnetic phase at the
critical temperature as
shown below.
References
[1].
[2].
[3].
[4].
[5].
[6].
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