Matching Magnetic Properties: List I and List II

This question requires matching concepts from List - I (Bloch wall, Anisotropy energy, Magnon, Curie Temperature) with their corresponding descriptions in List - II.

Explanation of Matches:

• A. Bloch wall is the boundary region that separates magnetic domains within a material. Therefore, it separates domains magnetised in different directions. This corresponds to Item III.
• B. Anisotropy energy is the energy associated with the directional dependence of magnetization in a magnetic material. It dictates that magnetization is preferred along specific crystallographic directions, known as easy axes. Thus, it directs the magnetisation along directions of easy magnetisation. This corresponds to Item I.
• C. Magnon is a quasiparticle representing a collective excitation of the magnetic order in ferromagnets, essentially a quantum of a spin wave. Therefore, it represents a quantised spin wave. This corresponds to Item IV.
• D. Curie Temperature ($T_C$) is a critical temperature above which ferromagnetic materials lose their spontaneous magnetization and become paramagnetic. Above this temperature, their magnetic susceptibility ($\chi$) follows the Curie-Weiss law: $\chi = \frac{C}{T - T_C}$. Thus, it is the temperature above which the susceptibility of a ferromagnetic material obeys Curie-Weiss Law. This corresponds to Item II.

Correct Matching:

Based on the explanations:

• A matches with III
• B matches with I
• C matches with IV
• D matches with II

The correct option is the one that reflects this matching: A-III, B-I, C-IV, D-II.