Difference Between Ferromagnetism and Antiferromagnetism

Key Difference – Ferromagnetism vs Antiferromagnetism
 

Ferromagnetism and antiferromagnetism are two of the five classifications of magnetic properties. The other three are diamagnetism, paramagnetism, and ferrimagnetism. The key difference between ferromagnetism and antiferromagnetism is that ferromagnetism can be found in materials having their magnetic domains aligned into the same direction whereas antiferromagnetism can be found in materials having their magnetic domains aligned in opposite directions.

A magnetic domain or an atomic moment is a  region in which the magnetic fields of atoms are grouped together and aligned. Ferromagnetic materials are attracted to an external magnetic field and have a net magnetic moment. But antiferromagnetic materials have a zero net magnetic moment.

CONTENTS

1. Overview and Key Difference
2. What is Ferromagnetism 
3. What is Antiferromagnetism
4. Side by Side Comparison – Ferromagnetism vs Antiferromagnetism in Tabular Form
5. Summary

What is Ferromagnetism?

Ferromagnetism is the presence of magnetic domains which are aligned into the same direction in magnetic materials. The most common examples of ferromagnetic materials are metals such as iron, nickel, cobalt and their metal alloys. The magnetic domains of these metals have strong interactions due to the electronic exchange between atoms. These strong interactions cause the alignment of magnetic domains in the same direction. Ferromagnetic materials exhibit parallel alignment of magnetic domains which results in the magnetization of the materials even in the absence of an external magnetic field.

Figure 1: Order of Magnetic Domains in Ferromagnetic Materials

Spontaneous Magnetization

The spontaneous magnetization is the magnetization of a material even in the absence of an external magnetic field. The magnitude of this magnetization is affected by the spin magnetic moment of electrons present in the ferromagnetic material.

High Curie Temperature

Curie temperature is the temperature at which the spontaneous magnetization starts to vanish. For ferromagnetic materials, this occurs at a high temperature.

What is Antiferromagnetism

Antiferromagnetism is the presence of magnetic domains that are aligned in opposite directions in magnetic materials. These opposite magnetic domains have equal magnetic moments which are canceled out (since they are in opposite directions). This makes the net moment of the material zero. This type of materials is known as antiferromagnetic materials.

Figure 2: Order of Magnetic Domains in Antiferromagnetic Materials

Common examples of antiferromagnetic materials can be found from transition metal oxides such as manganese oxide (MnO).

The Neel temperature (or the magnetic ordering temperature) is the temperature at which an antiferromagnetic material begins to be converted into a paramagnetic material. At this temperature, the thermal energy provided is large enough to break down the alignment of magnetic domains present in the material.

What is the Difference Between Ferromagnetism and Antiferromagnetism?

Summary – Ferromagnetism vs Antiferromagnetism

Materials can be divided into several groups based on their magnetic properties. Ferromagnetic and antiferromagnetic materials are such two types. The key difference between ferromagnetism and antiferromagnetism is that ferromagnetism can be found in materials having their magnetic domains aligned into the same direction whereas antiferromagnetism can be found in materials in which the magnetic domains are aligned in opposite directions.

Reference:

1. Classes of Magnetic Materials. Hitchhiker’s Guide to Magnetism, Available here.
2. “Néel Temperature.” Wikipedia, Wikimedia Foundation, 17 Feb. 2018, Available here.

Image Courtesy:

1. “Ferrimagnetic ordering” By Michael Schmid – Drawing created myself (CC BY-SA 3.0) via Commons Wikimedia
2. “Antiferromagnetic ordering” By Michael Schmid – Drawing created myself (CC BY-SA 3.0) via Commons Wikimedia

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