Magnet Myths and Misconceptions

[TinselKoala]

I need one of them ipads for when im on the road ,this phone screen to bloody small.
I have come up with a doozy idea as to how we can see the exact field shape of a PM. This I will do right after theo's free heat generating bismuth do'hicky experiment..I am about 1100km away from my workshop ATM, but should be home by the weekend, when I will whip up a quick demo of the non generating field.
@MarkE
What are the arrows on the field lines supose to represent-the flow of what?

As MarkE said, they represent "orientation", and the concentration represents "strength". But orientation of what? Strength of what? As you know, the field lines are just a convenient way of representing "something" and have no "real" existence, just like the elevation lines on a topographical map. On the topo map, the elevation contours tell you how steep the slope is in reality (by their 'bunching up') and the tiny numbers along them tell you the direction of the slope: that is, they tell you which way and how fast a "test particle" like a beachball will roll in the real terrain. For magnetic field lines, the arrow tells you in which direction a "test particle" -- here a hypothetical "magnetic monopole" -- would move, or how a tiny bipolar magnet like a compass needle would align, and the concentration or bunching of the field lines tell you how strongly such a test particle would move.  The magnetic field doesn't actually "flow", just as nothing flows on a topo map, and just as a road doesn't "go" anywhere. Test particles like beachballs, monopole magnetic particles, and road-trains "flow" along the real stationary elevation change, the stationary field lines, and the stationary road.

[MileHigh]

If one could construct perfectly stacked crystals of magnetic material, then the domain walls would be lined up like paving stones.  If the material were not magnetized, then the orientation of each domain would be randomly rotated.  Magnetizing the material would progressively bring the domains into greater and greater alignment.

Just to add a bit to what Mark said:  If you can imagine an "ideal" metallic crystal lattice, it would have no imperfections at all.  That means a perfect 3D arrangement of atoms, like a theoretical perfect diamond.  So you have your "paving stones" of individual magnetic domains within this "perfect diamond."  As you apply a perfectly uniform magnetic field to the paving stones, then you would start to get the merging of individual magnetic domains into larger magnetic domains.  In other words, the Bloch walls between individual magnetic domains would start to disappear.  At the limit, the entire magnetic crystal lattice would become a single domain.  That would represent a perfectly magnetized small crystal of metallic atoms where every single atomic magnetic dipole has the same orientation.

As was stated, every magnet has millions or billions of magnetic domains where the majority of the magnetic domains are oriented in the same direction.  Every magnet is not not a perfect metallic crystal lattice.  That is a description of the fine-grained architecture of any magnet.

Now, when it comes to the deluded folks that talk about a "Bloch wall at the center of a bar magnet," they never even discuss the fine-grained architecture of a magnet.  It's possible that they agree with the fine-grained architecture.  It's just as possible that they are not even thinking about this because they never mention it.  So ignorance strikes again.

So now let's shift our discussion to the incorrect notion of a Bloch wall at the center of a bar magnet.  What happens at this falsely imagined Bloch wall?   Well, as you can see I asked but I was unable to get a straight answer.

Here is a regular magnet:   [S>>>>>N]  The chevrons ('arrows') represent the majority of the magnetic domains lined up in the same direction.

Here is what I can only imagine that a magnet with a Bloch wall at the center looks like because the people that claim there is a Bloch wall at the center won't tell me:   [S>>>>|<<<<S]

As you can see, I am suggesting that the magnetic domains change direction by 180 degrees for a hypothetical Bloch wall at the center of a bar magnet.   The problem is that this makes no sense at all, and represents two sets of magnetic domains in opposition to each other resulting in mostly self-cancellation of the magnetic field.

This whole notion of a Bloch wall at the center of a magnet is a ridiculous nonsensical farce and is just another kind of "delayed Lenz effect" sickness.  It's just a mixture of arrogance, ignorance, and stupidity masquerading as "a new alternative way of looking at things."

When John Bedini explains to a crowd of grown men gathered around him at a conference that there is a Bloch wall in the center of a bar magnet and they all just nod in agreement, then he knows that he has bunch of suckers standing around him and chances are he can say just about anything to them so that they end up buying another useless DVD.

MileHigh

[synchro1]

I see you are still doing what you do best, Synchro: Misrepresenting the work of others, that you do not understand.

See if you can find such a photomicrograph that shows a "Bloch Wall" running along the center of a permanent magnet. Then try to explain why, when you cut a PM in half along the center, you get NOT two "monopole" magnets but rather two ordinary bipolar magnets, each with what you wrongly call a "Bloch wall" in their centers. It's a funny kind of "wall" that splits and moves just because you have cut along where you thought it was.

As MH told you earlier, Bloch walls are actually just what your photomicrographs show: Domain boundaries. And he has also told you the truth: In Permanent Magnets, most of the domains are oriented in the _same direction_ , not randomly like the images you have presented. Bloch walls exist between all the tiny magnetic domains that are randomly oriented, not along the "equator" of permanent magnets.

@TinselKoala,


Misrepresenting the work of others, that you do not understand.

"Ibid"  from an eccentric "Trash Harvester"!

Let's see what you make of it Einstien!

Abstract: 

"Domain-wall structure in thin films with perpendicular anisotropy: Magnetic force microscopy and polarized neutron reflectometry study".

"Ferromagnetic domain patterns and three-dimensional domain-wall configurations in thin CoCrPt films with perpendicular magnetic anisotropy were studied in detail by combining magnetic force microscopy and polarized neutron reflectometry with micromagnetic simulations. With the first method, lateral dimension of domains with alternative magnetization directions normal to the surface and separated by domain walls in 20-nm-thick CoCrPt films were determined in good agreement with micromagnetic simulations. Quantitative analysis of data on reflectometry shows that domain walls consist of a Bloch wall in the center of the thin film, which is gradually transformed into a pair of Néel caps at the surfaces. The width and in-depth thickness of the Bloch wall element, transition region, and Néel caps are found consistent with micromagnetic calculations. A complex structure of domain walls serves to compromise a competition between exchange interactions, keeping spins parallel, magnetic anisotropy orienting magnetization normal to the surface, and demagnetizing fields, promoting in-plane magnetization. It is shown that the result of such competition strongly depends on the film thickness, and in the thinner CoCrPt film (10 nm thick), simple Bloch walls separate domains. Their lateral dimensions estimated from neutron scattering experiments agree with micromagnetic simulations".

DOI: http://dx.doi.org/10.1103/PhysRevB.90.054425

1 MorePublished 28 August 2014
Received 9 May 2014
Revised 4 August 2014


©2014 American Physical Society                                              Here's the point:


                                                                           The "Bloch Wall' has physical dimensions:

                                                "Lateral dimensions of the "Bloch Wall" were measured by neutron scattering".

[MarkE]

Just to add a bit to what Mark said:  If you can imagine an "ideal" metallic crystal lattice, it would have no imperfections at all.  That means a perfect 3D arrangement of atoms, like a theoretical perfect diamond.  So you have your "paving stones" of individual magnetic domains within this "perfect diamond."  As you apply a perfectly uniform magnetic field to the paving stones, then you would start to get the merging of individual magnetic domains into larger magnetic domains.  In other words, the Bloch walls between individual magnetic domains would start to disappear.  At the limit, the entire magnetic crystal lattice would become a single domain.  That would represent a perfectly magnetized small crystal of metallic atoms where every single atomic magnetic dipole has the same orientation.

As was stated, every magnet has millions or billions of magnetic domains where the majority of the magnetic domains are oriented in the same direction.  Every magnet is not not a perfect metallic crystal lattice.  That is a description of the fine-grained architecture of any magnet.

Now, when it comes to the deluded folks that talk about a "Bloch wall at the center of a bar magnet," they never even discuss the fine-grained architecture of a magnet.  It's possible that they agree with the fine-grained architecture.  It's just as possible that they are not even thinking about this because they never mention it.  So ignorance strikes again.

So now let's shift our discussion to the incorrect notion of a Bloch wall at the center of a bar magnet.  What happens at this falsely imagined Bloch wall?   Well, as you can see I asked but I was unable to get a straight answer.

Here is a regular magnet:   [S>>>>>N]  The chevrons ('arrows') represent the majority of the magnetic domains lined up in the same direction.

Here is what I can only imagine that a magnet with a Bloch wall at the center looks like because the people that claim there is a Bloch wall at the center won't tell me:   [S>>>>|<<<<S]

As you can see, I am suggesting that the magnetic domains change direction by 180 degrees for a hypothetical Bloch wall at the center of a bar magnet.   The problem is that this makes no sense at all, and represents two sets of magnetic domains in opposition to each other resulting in mostly self-cancellation of the magnetic field.

This whole notion of a Bloch wall at the center of a magnet is a ridiculous nonsensical farce and is just another kind of "delayed Lenz effect" sickness.  It's just a mixture of arrogance, ignorance, and stupidity masquerading as "a new alternative way of looking at things."

When John Bedini explains to a crowd of grown men gathered around him at a conference that there is a Bloch wall in the center of a bar magnet and they all just nod in agreement, then he knows that he has bunch of suckers standing around him and chances are he can say just about anything to them so that they end up buying another useless DVD.

MileHigh

Has the DVD been "purified" by John Bedini's permanent magnet CD/DVD purifier?

[MarkE]

@TinselKoala,


Misrepresenting the work of others, that you do not understand.

"Ibid"  from an eccentric "Trash Harvester"!

Let's see what you make of it Einstien!

Abstract: 

"Domain-wall structure in thin films with perpendicular anisotropy: Magnetic force microscopy and polarized neutron reflectometry study".

"Ferromagnetic domain patterns and three-dimensional domain-wall configurations in thin CoCrPt films with perpendicular magnetic anisotropy were studied in detail by combining magnetic force microscopy and polarized neutron reflectometry with micromagnetic simulations. With the first method, lateral dimension of domains with alternative magnetization directions normal to the surface and separated by domain walls in 20-nm-thick CoCrPt films were determined in good agreement with micromagnetic simulations. Quantitative analysis of data on reflectometry shows that domain walls consist of a Bloch wall in the center of the thin film, which is gradually transformed into a pair of Néel caps at the surfaces. The width and in-depth thickness of the Bloch wall element, transition region, and Néel caps are found consistent with micromagnetic calculations. A complex structure of domain walls serves to compromise a competition between exchange interactions, keeping spins parallel, magnetic anisotropy orienting magnetization normal to the surface, and demagnetizing fields, promoting in-plane magnetization. It is shown that the result of such competition strongly depends on the film thickness, and in the thinner CoCrPt film (10 nm thick), simple Bloch walls separate domains. Their lateral dimensions estimated from neutron scattering experiments agree with micromagnetic simulations".

DOI: http://dx.doi.org/10.1103/PhysRevB.90.054425

1 MorePublished 28 August 2014
Received 9 May 2014
Revised 4 August 2014


©2014 American Physical Society                                              Here's the point:


                                                                           The "Bloch Wall' has physical dimensions:

                                                "Lateral dimensions of the "Bloch Wall" were measured by neutron scattering".

How do you think that anything in that cited quotation supports the idea of a "magnetic equator" in a permanent or electromagnet?