- #1
NTL01
- 21
- 3
I am having difficulty thinking through how a ferromagnetic substance is permanently magnetized.
I think I understand that when for example a sample of iron is heated above it curie temperature and then exposed to an external magnetic field , the sample will become permanently magnetized. The process involves the creation of domains that include some finite number of iron atoms, where the the magnetic moment of each atom is aligned to other atoms in the domain. The domains themselves become aligned to the external magnetic field, with parallel moment domains becoming larger and anti parallel smaller. When the sample cools , the domains become pinned into this parallel alignment , and the sample has a permanent magnetic field of its own
However each atoms magnetic moment is a result of the spin of its unpaired outer shell electron, which can be up or down. When many iron atoms all have their "free unpaired" electrons "up" there is an aggregate external magnetic moment to that sample. This is also true if all the electrons are "down"
Before the sample above was taken above Curie temperature we would expect the distribution of atoms with "up" and "down" spins to be random , where the ups and downs were adjacent , and the net effect is to produce a neutral external magnetic moment.
So my question:
When an external magnetic field is applied to a "hot " sample , and domains are created, are individual atoms "moving" within the sample to "line up" into adjacent groups ( domains) based on their electron spin? Sort of like all red cars going onto the top floor of the parking ramp). Or is the external magnetic field changing the spin of the electrons themselves so that along the lies of force of the external field, all the electrons are turned into "ups"? ( sort of like cars along a line get painted red)
I think I understand that when for example a sample of iron is heated above it curie temperature and then exposed to an external magnetic field , the sample will become permanently magnetized. The process involves the creation of domains that include some finite number of iron atoms, where the the magnetic moment of each atom is aligned to other atoms in the domain. The domains themselves become aligned to the external magnetic field, with parallel moment domains becoming larger and anti parallel smaller. When the sample cools , the domains become pinned into this parallel alignment , and the sample has a permanent magnetic field of its own
However each atoms magnetic moment is a result of the spin of its unpaired outer shell electron, which can be up or down. When many iron atoms all have their "free unpaired" electrons "up" there is an aggregate external magnetic moment to that sample. This is also true if all the electrons are "down"
Before the sample above was taken above Curie temperature we would expect the distribution of atoms with "up" and "down" spins to be random , where the ups and downs were adjacent , and the net effect is to produce a neutral external magnetic moment.
So my question:
When an external magnetic field is applied to a "hot " sample , and domains are created, are individual atoms "moving" within the sample to "line up" into adjacent groups ( domains) based on their electron spin? Sort of like all red cars going onto the top floor of the parking ramp). Or is the external magnetic field changing the spin of the electrons themselves so that along the lies of force of the external field, all the electrons are turned into "ups"? ( sort of like cars along a line get painted red)