What is a Hysteresis Loop?
The H-M relationship when plotted for all strengths of applied magnetic field, then the result is a hysteresis loop called the main loop. To sum it up,
- X-axis represents the strength of the applied magnetic field (H).
- Y-axis represents the magnetization within the material (B).
- The initial curve represents the magnetization process where the external field strength is increased from left to right, the material’s magnetization also increases but upwards. But there’s a delay, so the curve does not rise linearly as given in the figure below.
- And at a certain point, the material tends to be saturated with magnetic field, and further increases in H-look at the curve flattening out at the top.
- When the external field is reduced as it decreases towards the left, then magnetization follows a different curve that remains above the initial curve.
- The point where the loop intersects the y-axis at H = 0 represents the retentivity. And the point where the loop intersects the x-axis at B = 0 represents the coercivity.
- The area enclosed by the entire loop represents the energy lost as heat energy during this one cycle of magnetization & demagnetization.
Hysteresis Loop
Hysteresis Magnetism
Imagine a classroom setting at any school. Before the class begins, the students are engaged in various activity, some may be sitting oppositely in a bench to talk with someone or they might be running around etc. But as soon as the teacher arrives they occupy their benches facing same direction and even if teacher leaves they usually remain seated. This is what hysteresis magnetism is about. The teacher is like the external field and the students are the magnetic moments of materials and the benches are their domains.
Just as the students remain seated in a certain way even after the teacher leaves, magnetic materials are said to retain some magnetization even after the external magnetic field has changed or removed. This residual magnetization is because of hysteresis, where the material or the student(s) “remembers” its previous magnetization(orderly) state even after the external field has been changed or removed. This phenomenon is usually observed in ferromagnetic materials. (Also observed in Spin glasses). The way in which a piece of any magnetic material behaves when exposed to a changing magnetic field, tells a great deal about its properties.
Table of Content
- What is Hysteresis Magnetism?
- Types of Magnetic Hysteresis
- What is a Hysteresis Loop?
- Characteristics of Magnetic Hysteresis
- Properties of Hysteresis Magnetism
- Effects of Hysteresis Magnetism
- Working and Evolution of Hysteresis Magnetism:
- Difference between Magnetization and Demagnetization:
- Advantages and Disadvantages of Hysteresis Magnetism:
- Applications of Hysteresis Magnetism