Explain Anti Ferro-Magnetism using example of the MnO crystal.
Anti-ferromagnetism is a phenomenon in which magnetic moments of atoms or ions in a material align in an alternating pattern, causing the material to have no overall magnetic field. Let's take the example of the MnO crystal to understand this concept.
In the MnO crystal, manganese (Mn) and oxygen (O) atoms form a lattice structure. Each Mn atom has a magnetic moment, which is like a tiny magnet pointing in a specific direction. In a normal magnet, these magnetic moments align in the same direction, creating a strong magnetic field. However, in an anti-ferromagnetic material like MnO, the neighboring Mn atoms align their magnetic moments in opposite directions.
Imagine a row of Mn atoms in the crystal lattice. The first atom points its magnetic moment upwards, while the next one points downwards, and so on. This alternating pattern continues throughout the crystal. As a result, the magnetic moments cancel each other out, and the crystal doesn't exhibit any net magnetism.
Even though MnO is anti-ferromagnetic, it can still interact with an external magnetic field. When subjected to such a field, the crystal's magnetic moments may temporarily align, causing the material to exhibit weak magnetism. However, once the external field is removed, the alternating anti-ferromagnetic pattern is restored.
In summary, anti-ferromagnetism in the MnO crystal arises due to the alternating alignment of magnetic moments in the lattice, resulting in the absence of a net magnetic field.
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