This set of Nanotechnology Multiple Choice Questions & Answers (MCQs) focuses on “Surface and Bulk Magnetism of Materials”.
1. What does FLAPW method stands for?
a) Find Potential Linear Auger Plane Wave
b) Full Potential Linearized Augmented Plane Wave
c) Four Linearized Augmented Potential Wave
d) Five linear Auger Plane Wave
View Answer
Explanation: FLAPW method stands for Full Potential Linearized Augmented Plane Wave. It is a widely used method that provides a powerful frame for calculating magnetic surface or interface moments.
2. What happens when the basic symmetry is lost in a ferromagnetic surface?
a) Result in magnetic surface anisotropy
b) Result in torsion oscillation magnetometry
c) Result in ferromagnetic resonance
d) Result in Brillovin light scattering
View Answer
Explanation: The loss of basic symmetry in a ferromagnetic surface gives rise to a magnetic surface anisotropy. This indicates a magnetic contribution to the surface energy (ϭ) which is given as
ϭ = Kscos2ϑ
Here, ϑ is the angle between JS of a homogeneously magnetized sample and the normal to the surface.
3. Choose the correct option with respect to magnetic surface anisotropy (MSA).
a) MSA is independent of the chemical state of the surface
b) MSA for free surfaces is minimum
c) MSA of free surfaces depends on roughness
d) MSA was first experimentally confirmed in 1997
View Answer
Explanation: The first experimental confirmation of MSA was carried out in 1969. MSA necessarily depends on the chemical state of the surface. It tends to be maximum for free surfaces. This is however reduced heavily upon reaction with gas or any solid coating. The anisotropy of free surfaces varies with the roughness.
4. Surface has no effect on the domain wall structures.
a) True
b) False
View Answer
Explanation: Surface has a strong effect on the domain wall structures. In the volume, equilibrium wall structure is a Bloch wall that has a constant magnetization component orthogonal to the wall plane. This is free from stray-fields. If this Bloch wall is terminated by the surface, it gives rise to unfavourable stray-fields.
5. What is a magnetic live layer?
a) Bulk Curie temperature
b) Modified exchange interaction
c) Bulk anti-ferromagnetism
d) Surface magnetic order
View Answer
Explanation: Magnetic live layer is some kind of surface magnetic order attributed to the sufficiently enhanced exchange interactions near the surface. Curie temperature is referred to as the macroscopic measure from exchange interactions.
Sanfoundry Global Education & Learning Series – Nanotechnology.
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