5.2 Paramagnetism

Question 1

Describe the orientation of the magnetic moments (spins) when there is no applied field

Answer 1

Random as they are thermally agitated. No net magnetisation when there is no field applied

Question 2

Describe the orientation of the magnetic moments (spins) when there is an applied field

Answer 2

Start to align along the direction of the magnetic field, creating a non zero net magnetisation

Question 3

What is Curie paramagnetism?

Answer 3

When the magnetic susceptability is proportional to 1/T

Question 4

Describe the energy of an electron when its spin is aligned or not aligned with the magnetic field

Answer 4

It is lower if the spin is in the opposite direction to the magnetic field

Question 5

What happens to the densitites of states-Energy graph as the magnetic field is applied?

Answer 5

They are shifted for spin up and spin down, by μ_B B such that for an upward field, the number of spin up is < the number of spin down giving a non-zero magnetisation

Question 6

How is the value of the Pauli susceptability different for metals and non metals?

Answer 6

It is much smaller for non-metals