Magnetic materials

Magnetism-Superconductivity-spintronics-microfluidic applications

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

2. 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.

3. 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

4. Magnetic Induction B & Magnetic Field H Question : What is the relationship between B and H ? Answe r : 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

5. 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.

6. 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 Ferrimagnetic

7. Paramagnetic

8. Schematic representation of magnetism types