Adiabatic de-magnetization, process by which the removal of a magnetic field from certain materials serves to lower their temperature. Milli Kelvin temperatures could be achieved.

1. 4/3/2018 Department of Mechanical Engineering Confidential 1
PRESENTED BY:
MOHAMMAD AKRAM
ID NO: 172071011
M.TECH. (THERMAL ENGG.)
K L (Deemed to be) UNIVERSITY.

2. What’s Adiabatic Demagnetization.?
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MagnetoCaloric Effect
 It’s a Magneto-Thermodynamic phenomenon in which a temperature change of
a suitable material is caused by exposing the material to a changing magnetic field
 Working Principle
 Just an another method of producing low temperatures(Around small fraction of 1K)
and occurs in magneto-caloric materials.

3.  Isothermal compression of a gas Isothermal magnetisation of a paramagnet
(we apply pressure and the entropy decreases) (we apply H and the magnetic entropy decreases)
 Subsequent Adiabatic Expansion Adiabatic demagnetisation
(we lower pressure at constant S and T decreases) (we remove H, the total S remains constant and
T decreases since the magnetic entropy increases)
Analogous to
Analogous to

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Temperature System’s HotnessTells us about

5. Process of Lowering Temperature of a Paramagnetic Salt
1) Isothermal Magnetization
2) Adiabatic Demagnetization
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6. Experimental Procedure
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The sample is cooled to the boiling point of helium in strong magnetic field,thermally
Isolated... and then…. removed from the field to demagnetize it.

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9. Adiabatic Nuclear Demagnetization
 This process relies on aligning nuclear dipoles (arising from nuclear spins),
which are at least 1,000 times smaller than those of atoms
 16 micro-degrees (0.000016 degree) absolute could be reached!!
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Thank
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