SILVER OAK COLLEGE OF ENGG. & TECHNOLOGY SUBJECT :- Magnetic Material Prepared by :- JAY DESAI Branch :- Computer Roll no. :- CE – A 26 Enrollment no. :

MAGNETIC MATERIALS

Classification of magnetic materials Diamagnetic Materials Paramagnetic Materials Ferromagnetic Materials Antiferromagnetic Material Ferrimagnetic Materials

Diamagnetic Materials The diamagnetic substances are those in which the individual atoms or ions do not possess any net magnetic moment on their own. When such substances are placed in an external magnetizing field, they get feebly magnetized in a direction opposite to a magnetizing field.

Paramagnetic Substances Paramagnetic substances are those in which each individual atom or molecule or ion has a net non zero magnetic moment of its own. When such substances are placed in an external magnetic field, they get feebly magnetized in the direction of the magnetizing field.

Ferromagnetic materials Ferromagnetic material are those in which each individual atom or molecule has a non zero magnetic moment. Ferromagnetic Domains in Materials.

Antiferromagnetic Material In Antiferromagnetic material magnetic dipoles are parallel to each other. The antiparallel alignment exists in material below a critical temerature is called as NEEL TERMERATURE. Antiferromagnetic material dipole arrangements.

Ferrimagnetic Materials Ferrimagnetic Materials are special case of antiferromangetic material. The magnetic dipoles are antiparallel, similar to antiferromangetic however there magnitude are not similar. Ferrimagnetic material dipole arrangements.

Hysteresis Materials Hysteresis occurs in ferromagnetic materials and ferroelectric materials, as well as in the deformation of some materials in response to a varying force. When an external magnetic material is applied to a ferromagnetic material such as iron, the atomic dipoles align themselves with it.

If the magnetic field is now reduced monotonically, M follows a different curve. At zero field strength, the magnetization is offset from the origin by an amount called the retentivity. If the H-M relationship is plotted for all strengths of applied magnetic field the result is a hysteresis loop called the main loop. The width of the middle section is twice the coercivity of the material.

Soft Magnetic Material Soft magnetic material is used in CD/DVD, Floppy disk The is very much lighter and so it used in headphones also. There Retentivity, coercive, eddy current, saturation is low. Exmaples are different alloys.

Hard Magnetic Material Soft magnetic material is used in Hard disk. This type of material is mostly used in storage. There Retentivity, coercive, eddy current, saturation is High. Exmaples are different Ferriles, Granets.

Applications of magnetic material Generally, magetic material plays a dominant role in storage as well as recording/reading applications. A few exmaples of magnetic material are speaker, floppy disk, hard disk, Radio, headphone, CD/DVD drives. The data can be write or store into disk by two method :- (i)Digital Recording (ii)Analog Recording

Magnetic Tape Storage Magnetic tape storage is sequential access memory and is capable of having a very large capacity at a very low cost. Magnetic tape is a plastic tape about ½ inch wide, coated with a magnetic surface, identical to the tape used in home recording. The quality of material used in however much higher than that used in domestic purposes. The material used for coating is ferric oxide.

Floppy Disk Storage The floppy disk is a flexible plastic base disk.it can be easily plugged in the drive mechanism as a tape cassette. The disk is interred in the drive with the envelope in place. This is because the envelope provides protection to the recording surface which is about 100µ in thick layer of magnetic oxide. The normal capacity of a floppy disk is 1.4 MB. The speed of rotation is approximately 360 R.P.M.

Working of Floppy Disk

Magnetic Disk Storage Magnetic disk storage is based on the same physical phenomena as that of magnetic drum. Their external characters as seen by the system designer are essentially the same. They differ in mechanical structure. The metal disk coated with ferromagnetic material rotates under one or more read/write heads. The speed of rotation is typically 1800 or 3600 R.P.M. The latest magnetic disk storages have speed up to 7200 R.P.M.

Images of Magnetic Hard Disk

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