Magnetic susceptibility is a property that measures how much a material becomes magnetized when exposed to an external magnetic field. It indicates the degree to which a material can be magnetized and reflects how it responds to magnetic forces.
This property is defined as the ratio of the magnetization (M) induced in the material to the applied magnetic field (H). Based on the sign and magnitude of magnetic susceptibility, materials can be classified into different types:
- Diamagnetic materials (e.g., bismuth, copper): Have negative susceptibility; they create a weak magnetic field in opposition to the applied field.
- Paramagnetic materials (e.g., aluminum, oxygen): Have small positive susceptibility; they are weakly attracted to magnetic fields.
- Ferromagnetic materials (e.g., iron, cobalt): Have large positive susceptibility; they become strongly magnetized and can retain magnetism even after the external field is removed.
Magnetic susceptibility plays a key role in:
- Material science (designing magnetic devices),
- Geophysics (studying Earth’s magnetism),
- Medical imaging (like MRI),
- Condensed matter physics (understanding magnetic phase transitions).
It provides insight into the electronic structure and magnetic behavior of different materials under external magnetic influence.