Magnetic Properties
Magnetic Properties of Solids
Magnetic Properties
Magnetic (with unpaired electron) Materials Non-magnetic or diamagnetic (electrons all paired up)
Paramagnetic Ferromagnetic Antiferromagnetic Ferrimagnetic
Magnetic Behavior
B = μH B = μ0H + μ0M
Induction generated Induction generated by the field by the sample
B: magnetic flux density μ: permittivity (m0: free space) H: magnetic field M: Magnetization
χ = M/H
χ: magnetic susceptibility
B = μ0H + μ0Hχ B = μ0H (1 + χ) = μH μ0 (1 + χ) = μ (1 + χ) = μ / μ0 = μr μr: relative permittivity
Behavior of Substances in a Magnetic Field
Magnetic behavior may be distinguished by the values of χ and μ and by their temperature and field dependence 1. Positive vs. negative value: only diamagnetic materials show negative χ 2. Absolute value: ferromagnetic materials show huge positive value 3. Temperature dependence: diamagnetism is not temp. dependence, antiferromagentic materials increase with increasing temp, and para- and ferromagnetic materials decrease with increasing temp 4. Field dependence: only ferro- and antiferromagnetic materials show field dependence
Effect of Temperature
Paramagnetic substance: obey Curie Law
C: Curie constant T: temperature
There is no spontaneous interaction between adjacent unpaired electrons. With increasing temperature the alignment is more difficult and χ decreases.
Paramagnetic substance show some magnetic ordering (ferro- or antiferro): Curie-Weiss Law χ= C Τ-θ θ: Weiss constant
There is some spontaneous interaction between adjacent spins. A better fit to the high temperature behavior in the paramagnetic region is provided by Curie-Weiss Law (with additional Weiss constant).
Effect of Temperature
Paramagnetic: Curie law; T decrease, c increase (alignment easier)
Robert John Lancashire (wwwchem.uwimona.edu.jm)
Tc: ferromagnetic Curie temperature (below Tc, sample is ferromagnetic) TN: Néel Temperature (below TN, sample is
Magnetic Properties
Magnetic (with unpaired electron) Materials Non-magnetic or diamagnetic (electrons all paired up)
Paramagnetic Ferromagnetic Antiferromagnetic Ferrimagnetic
Magnetic Behavior
B = μH B = μ0H + μ0M
Induction generated Induction generated by the field by the sample
B: magnetic flux density μ: permittivity (m0: free space) H: magnetic field M: Magnetization
χ = M/H
χ: magnetic susceptibility
B = μ0H + μ0Hχ B = μ0H (1 + χ) = μH μ0 (1 + χ) = μ (1 + χ) = μ / μ0 = μr μr: relative permittivity
Behavior of Substances in a Magnetic Field
Magnetic behavior may be distinguished by the values of χ and μ and by their temperature and field dependence 1. Positive vs. negative value: only diamagnetic materials show negative χ 2. Absolute value: ferromagnetic materials show huge positive value 3. Temperature dependence: diamagnetism is not temp. dependence, antiferromagentic materials increase with increasing temp, and para- and ferromagnetic materials decrease with increasing temp 4. Field dependence: only ferro- and antiferromagnetic materials show field dependence
Effect of Temperature
Paramagnetic substance: obey Curie Law
C: Curie constant T: temperature
There is no spontaneous interaction between adjacent unpaired electrons. With increasing temperature the alignment is more difficult and χ decreases.
Paramagnetic substance show some magnetic ordering (ferro- or antiferro): Curie-Weiss Law χ= C Τ-θ θ: Weiss constant
There is some spontaneous interaction between adjacent spins. A better fit to the high temperature behavior in the paramagnetic region is provided by Curie-Weiss Law (with additional Weiss constant).
Effect of Temperature
Paramagnetic: Curie law; T decrease, c increase (alignment easier)
Robert John Lancashire (wwwchem.uwimona.edu.jm)
Tc: ferromagnetic Curie temperature (below Tc, sample is ferromagnetic) TN: Néel Temperature (below TN, sample is