M.Sc. (Physics-Material Science) (Semester IV)
(CBCS) Examination, 2017
MAGNETIC MATERIALS
Day Date: Monday, 24-04-2017 Max Marks: 70
Time: 02.30 PM to 5.00 PM
Instruction: Question no. 1 and 2 are compulsory.
Attempt any 3 questions from Q. no. 3 to Q. no. 7.
Figures to the right indicate full marks.
Q.1 Choose correct alternatives. 10
The orbital angular magnetization of an electron in




The typical value for the exchange energy between two
neighboring moments in a ferromagnetic crystal is

is
Paramagnetic ferromagnetic
antiferromagnetic ferrimagnetic
In SI units, tesla is expressed as
None of the above
The magnetization of a solid, magnetic induction B and
field strength H are related by


If is the Neel temperature for an antiferromagent, its
susceptibility is given by




The phenomenon in which a change in the shape of certain
ferromagnetic material is produced when they are subjected
a magnetic field, in known as
Electrostriction Magnetostriction
Page 2 of 2
Piezoelectric effect Anisotropic effect
Magnetic Susceptibility for a
Metal Semiconductor
Insulator Superconductor
State True or False: 06
The temperature below which certain materials are
ferromagnetic and above which they are paramagnetic is
called Neel temperature.
The garnet has chemical formula .
For a ferromagnet, Exchange integral J is positive and spins
are parallel.
The typical value of the thickness of the Bloch wall is 1000 Å.
Curie law is valid for paramagnet.
Magnetic induction B and magnetic field intensity H are
related by .
Q.2 Write short notes of the following. 08
Shapes of hysteresis loops
Hexagonal ferrites
Domain wall structure
Q.3 Explain the molecular field theory above and below in
antiferromagntism.
08
Write a note on magnetic resonance.
06
Q.4 Discuss the effect of stress on magnetostriction and explain the
applications of magnetostriction.
08
Write a short note on antiferromagnetic alloys.
06
Q.5 Discuss the spinal cubic structure of ferrites and explain how the
saturation magnetization of ferrites depends on the site
occupancy of A and B site of spinal lattice.
08
Discuss the magnetic Measurements in Open Circuits.
06
Q.6 Discuss the magnetic characteristics of diamagnetic,
paramagnetic, ferromagnetic, antiferromagnetic and
ferrimagnetic materials on account of their magnetic on account
of their magnetic moments as well as magnetic susceptibilities.
08
Discuss the theories of ferromagnetism.
06
Q.7 Give an account for molecular field theory of ferromagnetism. 08
Discuss the concept of exchange forces.
06