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Antiferromagnetism
(NORASHIDA MOHD RAZALI,4SSCZ) (Geometry lead to…
Antiferromagnetism
(NORASHIDA MOHD RAZALI,4SSCZ)
Introduction
:explode: hard magnet = retain magnetism easily,useful in data memory storing
:explode:magnetic material varying degree of magnetism characterized by:
(lead to 5 types of magnetism)
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Ferromagnets
:check:+ve χ,magnetic moment align parallel with applied external field.
:check:maintain magnetism even field is removed.
:check:above critical T = paramagnet
-magnetic moment align in general direction of field,
-alignment weaker than above critical T
-material not retain magnetism when field removed.
:
Antiferromagnets
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:<3: below critical T (Tn) = alignment occur spontaneously
:<3:above critical T=material is paramagnetic
:<3:less common,observed at low T
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Temperature dependence
:shirt:above Tn=material as paramagnetic,magnetic moment align with field
:shirt:below Tn=magnetic moment spontaneously align,M=0 due to cancel of sublattices.
Curie's Law
Curie-Weiss law
:shirt:increase χ above T leads to -θ so CW law:
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