Antiferromagnetism and permanent moments — true or false? “Antiferromagnetic materials do not possess permanent magnetic dipole moments.”

Introduction / Context:
Magnetic ordering types (ferromagnetism, antiferromagnetism, ferrimagnetism) are distinguished by how atomic moments arrange. A careful reading is needed to separate the existence of individual moments from the net bulk magnetization.

Given Data / Assumptions:

• Antiferromagnets have two or more sublattices with opposing ordered moments below the Néel temperature T_N.
• Moments arise from unpaired electron spins on atoms/ions.
• Macroscopic net magnetization can be zero even when local moments exist.

Concept / Approach:
In antiferromagnets, atoms carry permanent magnetic dipole moments, but the crystal arranges these moments antiparallel so that the vector sum is approximately zero. Thus, saying antiferromagnets “do not have permanent dipoles” is false; they do, but they cancel in aggregate.

Step-by-Step Solution:
Identify local physics: unpaired spins → permanent moments on ions.Identify ordering: equal and opposite sublattices → cancellation of net M.Conclude statement is false: local moments exist, net magnetization tends to zero.

Verification / Alternative check:
Neutron diffraction detects ordered spin arrangements in antiferromagnets, directly confirming the presence of permanent moments despite zero macroscopic M.

Why Other Options Are Wrong:
“True” ignores local moments. “False; equal to ferromagnets” overstates the net magnetization. “Indeterminate” is unnecessary because the definition clarifies the point.

Common Pitfalls:

• Equating “no net magnetization” with “no permanent moments.”
• Confusing antiferromagnetism with diamagnetism (χ < 0, induced only).

Final Answer:
False