Magnetic material

1. K.Loganathan
Materials Chemistry
Ist –M.Sc-Chemistry

4.  Magnetic Materials: These materials are attracted by magnetic field.
Iron, nickel and cobalt objects such as iron nail, key, metal spade,
needle and metal door handle are magnetic in nature.
 Non-Magnetic Materials: These materials are not attracted towards
magnet. For example; wood, rubber, plastics, coins, leather and feather
are non-magnetic in nature.
Materials which are capable to being magnet in magnetic field are called as magnetic materials.
Metals like iron, nickel, cobalt and their compounds and alloys are magnetic in nature.
Magnetic materials can be classified in two types.
Soft magnetic materials: These materials do not have permanent magnetism and lose their magnetism
quickly in the absence of magnetic field. They form temporary magnets and also known as electromagnet.
The best examples of soft magnet are iron-silicon alloys, nickel-iron alloy and iron.
Hard magnetic materials: These magnetic materials retain their magnetism in absence of magnetic
field and also known as permanent magnets. Alloys composed of iron, cobalt and aluminum are generally
acted as hard magnetic materials.

5. Magnetic field
 Magnetic field is a force which is generated due to energy
change in a volume of space
 A magnetic field is produced by an electrical charge in motion
e.g. current flowing in a conductor, orbital movement and spin of
electrons Magnetic lines of force
Current
Magnetic lines of force

7. Magnetic Induction B & Magnetic Field H
Question: What is the relationship between B and H?
Answer: When a magnetic field has been generated in a medium by a
current in accordance with Ampere’s law,
the medium will respond with a magnetic induction B
( “magnetic flux density”)
The magnetic “flux density” is given in webers/m2 = B
1 weber per square meter = 1 Tesla

9. Magnetic moments
 Being a moving charge, electrons produce a small magnetic
field having a magnetic moment along the axis of rotation.
 The spin of electrons also produces a magnetic moment
along the spin axis.
 Magnetism in a material arises due to alignment of magnetic
moments.

10. Types of Magnetisms
 Depending on the existence and alignment of magnetic
moments with or without application of magnetic field, three types of
magnetism can be defined.
 Diamagnetic
 Paramagnetic
 Ferromagnetic
 Antiferromagnetic

13. Paramagnetic

20. Schematic representation of magnetism
types