What type of substances exhibit antiferromagnetism ?

Explanation

### Step-by-Step Solution:

1. **Definition of Antiferromagnetism**:
Antiferromagnetism is a type of magnetic ordering in which adjacent magnetic moments (spins) align in opposite directions. This means that the magnetic dipoles cancel each other out, resulting in a net magnetic dipole moment of zero.

2. **Characteristics of Antiferromagnetic Substances**:
- In antiferromagnetic materials, the magnetic moments of atoms or ions are arranged in such a way that they oppose each other.
- This opposing arrangement leads to the cancellation of the magnetic moments, resulting in no net magnetization.
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