MATERIALS BASED ON THEIR MAGNITIZATION.pptx

MATERIALS BASED ON THEIR MAGNITIZATION.pptx

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  LOYOLA INSTITUTE OFTECHNOLOGY Palanchur, Chennai–600123 PH3256 – PHYSICS FOR INFORMATION SCIENCE UNIT III – MAGNETIC MATERIALS MAGNETIC MATERIALS
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  LOYOLA INSTITUTE OFTECHNOLOGY Palanchur, Chennai–600123 PH3256 – PHYSICS FOR INFORMATION SCIENCE UNIT III – MAGNETIC MATERIALS • The materials which strongly attract a piece of iron are known as magnetic materials or magnets • The magnetic property of a material arises due to the magnetic moment or magnetic dipole of materials. • Materials which are magnetized by the application of an external field are known as magnetic materials.
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  LOYOLA INSTITUTE OFTECHNOLOGY Palanchur, Chennai–600123 PH3256 – PHYSICS FOR INFORMATION SCIENCE UNIT III – MAGNETIC MATERIALS • Diamagnetic materials - no permanent magnetic moment • Paramagnetic, ferro magnetic, antiferromagnetic and ferro magnetic materials - possess permanent magnetic moment Classification of magnetic materials
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  LOYOLA INSTITUTE OFTECHNOLOGY Palanchur, Chennai–600123 PH3256 – PHYSICS FOR INFORMATION SCIENCE UNIT III – MAGNETIC MATERIALS • In the presence of a magnetic field, dipoles are induced and aligned opposite to the field direction. Diamagnetic materials
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  LOYOLA INSTITUTE OFTECHNOLOGY Palanchur, Chennai–600123 PH3256 – PHYSICS FOR INFORMATION SCIENCE UNIT III – MAGNETIC MATERIALS • They do not have a permanent dipole moment. • Magnetic effects are very weak and hence, often masked by other kind of magnetism. • The magnetisation becomes zero on removal of the external field • The susceptibility of a diamagnetic material is negative. • The susceptibility is independent of temperature and external field. Properties of Diamagnetic materials
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  LOYOLA INSTITUTE OFTECHNOLOGY Palanchur, Chennai–600123 PH3256 – PHYSICS FOR INFORMATION SCIENCE UNIT III – MAGNETIC MATERIALS • They repel the magnetic lines of force. The existence of this behaviour in a diamagnetic material is shown above. • Examples: Copper, Gold, Mercury, Silver and Zinc. Properties of Diamagnetic materials
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  LOYOLA INSTITUTE OFTECHNOLOGY Palanchur, Chennai–600123 PH3256 – PHYSICS FOR INFORMATION SCIENCE UNIT III – MAGNETIC MATERIALS • The behaviour of a paramagnetic material under the influence of an external field is shown below Paramagnetic materials
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  LOYOLA INSTITUTE OFTECHNOLOGY Palanchur, Chennai–600123 PH3256 – PHYSICS FOR INFORMATION SCIENCE UNIT III – MAGNETIC MATERIALS • Paramagnetic material possess a permanent dipole moment. • They attract the magnetic lines of force. • The susceptibility is positive and depends on temperature: equation is known as the Curie law of paramagnetism. • Paramagnetic susceptibility is inversely proportional to temperature. • Examples: Aluminium, chromium, sodium, titanium. zirconium, etc. Properties of Paramagnetic materials
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  LOYOLA INSTITUTE OFTECHNOLOGY Palanchur, Chennai–600123 PH3256 – PHYSICS FOR INFORMATION SCIENCE UNIT III – MAGNETIC MATERIALS • Mutual alignment of atomic dipoles even in the absence of an external magnetic field. The coupling forces align the magnetic spins. Ferromagnetic materials
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  LOYOLA INSTITUTE OFTECHNOLOGY Palanchur, Chennai–600123 PH3256 – PHYSICS FOR INFORMATION SCIENCE UNIT III – MAGNETIC MATERIALS • The magnetic dipoles are arranged parallel to each other. • The spin arrangement is shown below Properties of Ferromagnetic materials
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  LOYOLA INSTITUTE OFTECHNOLOGY Palanchur, Chennai–600123 PH3256 – PHYSICS FOR INFORMATION SCIENCE UNIT III – MAGNETIC MATERIALS • They have characteristic temperature, namely, ferromagnetic Curie temperature (f). Materials below f behave as ferro magnetic materials and obey hysteresis curve. A material behave as a paramagnetic when it is above f. • They possess permanent dipole moment. • The susceptibility of a ferromagnetic material is • Examples: Iron, Cobalt, Nickel Properties of Ferromagnetic materials
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  LOYOLA INSTITUTE OFTECHNOLOGY Palanchur, Chennai–600123 PH3256 – PHYSICS FOR INFORMATION SCIENCE UNIT III – MAGNETIC MATERIALS • The antiparallel alignment exists in material below a critical temperature known as Neel temperature. Antiferromagnetic materials
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  LOYOLA INSTITUTE OFTECHNOLOGY Palanchur, Chennai–600123 PH3256 – PHYSICS FOR INFORMATION SCIENCE UNIT III – MAGNETIC MATERIALS • The dipoles are aligned antiparallel as shown in figure. • When the temperature increases, susceptibility increase and reaches a maximum at a temperature known as Neel temperature beyound which it decreases. • The value of susceptibility is positive an is vey small when T is greater then the Neel temperature Tn • Examples: Ferrous oxide, manganese oxide, manganese sulphite, chromium oxide, etc. Properties of Antiferromagnetic materials
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  LOYOLA INSTITUTE OFTECHNOLOGY Palanchur, Chennai–600123 PH3256 – PHYSICS FOR INFORMATION SCIENCE UNIT III – MAGNETIC MATERIALS • A special case of antiferromagnetic materials. • The magnetic dipoles are antiparallel. • However, their magnitudes are not equal. • Hence, they produce a large magnetization even for a small applied external magnetic field. Ferrimagnetic materials
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  LOYOLA INSTITUTE OFTECHNOLOGY Palanchur, Chennai–600123 PH3256 – PHYSICS FOR INFORMATION SCIENCE UNIT III – MAGNETIC MATERIALS • The dipoles are antiparallel as shown in figure. However, the dipoles are not equal in magnitude. • Net magnetization is larger even for a small external field. • The susceptibility is positive and very large when the temperature is higher than Tn • They behave as paramagnetic and ferromagnetic materials respectively above and below Curie temperature. Properties of Ferrimagnetic materials