Difference Between Paramagnetism, Diamagnetism And Ferromagnetism

Paramagnetism

Paramagnetism is a form of magnetism whereby some materials are weakly attracted by an externally applied magnetic field and form internal induced magnetic fields in the direction of the applied magnetic field.

Materials or substances that display Paramagnetism are referred to as paramagnetic. Some compounds and most chemical elements are paramagnetic under certain circumstances. However, true paramagnets display magnetic susceptibility according to the Curie or Curie-Weiss laws and exhibit Paramagnetism over a wide temperature range. 

Examples of paramagnetic substances/materials include:

• Aluminium
• Platinum
• Manganese
• Chromium
• Titanium
• Sodium
• Calcium
• Lithium
• Tungsten
• Niobium
• Copper chloride
• Crown glass
• Oxygen etc

What You Need To Know About Paramagnetic Material/substances

• They can be solid, liquid or gas.
• Every atom is a magnetic dipole having a resultant magnetic moment.
• Paramagnetic substances are weakly attracted by an external magnetic field.
• Paramagnetic substances lose their magnetism on removal of the external magnetic field.
• They tend to move from the weaker to the stronger part of the field when placed in a non-uniform magnetic field.
• They get weakly magnetized in the same direction to that of the field in an external magnetic field.
• When a rod of a paramagnetic substance is suspended in a uniform magnetic field, it comes to rest with its length parallel to the direction of the field.
• Magnetic susceptibility for paramagnetic substances is positive and small.
• The susceptibility of paramagnetic material decreases with an increase in temperature.
• The net magnetic moment of the paramagnetic substance is zero because in absence of an external magnetic field, the magnetic moments of atomic magnets are randomly arranged.
• If a watch glass containing a small quantity of paramagnetic liquid is placed on two unrelated magnetic poles, the liquid shows an elevation in the middle.
• If a magnetic field is applied to the paramagnetic liquid in one arm of U-tube, the liquid level in that arm rises.
• If paramagnetic gas is introduced between pole pieces of magnet, it spreads in the direction of the magnetic field.

Diamagnetism

Diamagnetism is a very weak form of magnetism that is induced by a charge in the orbital motion of electrons due to an applied magnetic field. This magnetism is nonpermanent and persists only in the presence of an external field. The magnitude of the induced magnetic moment is very small and its direction is opposite to that of the applied field.

Diamagnetism is found in all materials but because it is so weak, it can be observed only when other types of magnetism are totally absent hence it is of no practical importance.

Examples of diamagnetic materials/substances include:

• Bismuth
• Antimony
• Copper
• Marble
• Zinc
• Graphite
• Silver
• Nitrogen
• Gold
• Quartz
• Mercury
• Water
• Alcohol
• Air
• Hydrogen etc

What You Need To Know About Diamagnetic Material

• They can be solid, liquid or gas.
• The magnetic moment of every atom of diamagnetic substance/material is zero.
• Diamagnetic materials/substances are weakly repelled by an external magnetic field.
• Diamagnetic substances/material lose their magnetism on removal of the external magnetic field.
• Diamagnetic material/substance tends to move from the stronger to the weaker part of the field.
• Diamagnetic materials get weakly magnetized in direction opposite to that of the field.
• When a rod of diamagnetic substance/material is suspended in a uniform magnetic field, it comes to rest with its length perpendicular to the directions of the field.
• Magnetic susceptibility of diamagnetic substance/material is negative.
• Temperature has no effect on diamagnetic material/substance.
• The net magnetic moment of diamagnetic substance is zero in the absence of an external magnetic field.
• If a watch glass containing a small quantity of diamagnetic liquid is placed on two dissimilar magnetic poles, the liquid shows a depression in the middle.
• If a magnetic field is applied to a diamagnetic liquid in one arm of U-tube, the liquid level in that arm is lowered.
• If diamagnetic gas is introduced between pole pieces of magnet, it spreads at a right angle to the magnetic field.

Ferromagnetism

Ferromagnetism can be described as a physical phenomenon in which certain materials attain permanent magnetism or they acquire attractive powers. It is also described as a process where some of the electrically uncharged materials attract each other strongly.  Ferromagnetism is a property that considers not only the chemical composition of a material but also takes into consideration the microstructure and crystalline structure.

In a ferromagnetic material in the umagnetized state, atomic dipoles in small regions referred to as domains are aligned in the same direction. The domains exhibit a net magnetic moment even in the absence of an external magnetizing field.

However, the magnetic moments of neighboring domains are oriented in opposite directions. They cancel out and therefore the net magnetic moment of the material is zero. On application of external magnetic field, these domains all align themselves in the direction of the applied field.  In this regard, the material is strongly magnetized in a direction parallel to the magnetizing field.

Ferromagnetic materials can retain their magnetization when the external field is removed, as long as the temperature is below a critical value, the Curie temperature.  They are characterized by a large positive magnetic susceptibility.

Examples of Ferromagnetic substances/materials include:

• Iron
• Cobalt
• Nickel
• Gadolinium
• Metallic alloys
• Rare earth magnets

What You Need To Know About Ferromagnetic Substances/Material

• They are solid.
• Ferromagnetic substances/material consists of a large number of small domains. The atomic magnets in one domain are aligned in the same direction due to strong interaction.
• Ferromagnetic material/substance are strongly attracted by external magnetic field.
• Ferromagnetic material/substances do not lose magnetism when the external magnetic field is removed i.e they are permanent magnets.
• Ferromagnetic material tends to move from the weaker to the stronger part of the field.
• Ferromagnetic material/substance get strongly magnetized in the same direction to that of the field.
• When a rod of a ferromagnetic substance is suspended in a uniform magnetic field, it comes to rest with its length parallel to the directions of the field.
• Magnetic susceptibility of ferromagnetic material/substance is positive and large.
• When heated above Curie temperature, ferromagnetic material/substance becomes paramagnetic.
• The net magnetic moment of a ferromagnetic substance is zero because in the absence of an external magnetic field, the magnetic moments of domains are randomly arranged.

Also Read: Difference Between Permanent Magnet And Electromagnet

Difference Between Diamagnetic, Paramagnetic And Ferromagnetic Materials In Tabular Form