# What is the Magnetization of a Material?

## Answer #1

The **magnetization** \( \boldsymbol{M} \) describes the magnetic properties of a material. It is formed by the sum of all atomic **magnetic moments** \( \boldsymbol{\mu} \) per **volume** \( V \):

**Definition of magnetization**

If you apply an **external magnetic field** \(\boldsymbol{H}\) (or equivalently \(\boldsymbol{B}\)) and place a material into this magnetic field, the material will behave differently depending on the magnitude of the magnetization:

**Magnetization depends on the external magnetic field**

Here \(\chi\) is the **magnetic susceptibility**, which determines how good a material can be magnetized.

If the magnetic susceptibility is negative: \( -1 \lt \chi \lt 0 \), then the material is

*diamagnetic*. (Note that \(\chi\) cannot be less than -1. A superconductor has \(\chi = -1 \) and is a perfect diamagnet).If the magnetic susceptibility is positive: \( \chi \gt 0 \), then the material is

*paramagnetic*.If the magnetic susceptibility is much greater than zero: \( \chi \gg 0 \), then the material is

*ferromagnetic*.