Supercomputers Help Researchers Find Two New Kinds Of Magnets (phys.org) 79
"Predicting magnets is a heck of a job, and their discovery is very rare," said a mechanical engineering professor at Duke University. But after years of work synthesizing various predictions, material scientists "predicted and built two new magnetic materials, atom-by-atom, using high-throughput computational models." An anonymous reader quotes Phys.org:
The success marks a new era for the large-scale design of new magnetic materials at unprecedented speed. Although magnets abound in everyday life, they are actually rarities -- only about 5% of known inorganic compounds show even a hint of magnetism. And of those, just a few dozen are useful in real-world applications because of variability in properties such as effective temperature range and magnetic permanence...
In a new study, materials scientists from Duke University provide a shortcut in this process. They show the capability to predict magnetism in new materials through computer models that can screen hundreds of thousands of candidates in short order. And, to prove it works, they've created two magnetic materials that have never been seen before.
"The first alloy is particularly interesting," reports the International Business Times, "because it contains no rare-earth materials, which are both expensive and difficult to acquire." But a Duke mechanical engineering professor points out that "It doesn't really matter if either of these new magnets proves useful in the future. The ability to rapidly predict their existence is a major coup and will be invaluable to materials scientists moving forward."
In a new study, materials scientists from Duke University provide a shortcut in this process. They show the capability to predict magnetism in new materials through computer models that can screen hundreds of thousands of candidates in short order. And, to prove it works, they've created two magnetic materials that have never been seen before.
"The first alloy is particularly interesting," reports the International Business Times, "because it contains no rare-earth materials, which are both expensive and difficult to acquire." But a Duke mechanical engineering professor points out that "It doesn't really matter if either of these new magnets proves useful in the future. The ability to rapidly predict their existence is a major coup and will be invaluable to materials scientists moving forward."
Question for the Physicists. (Score:1)
I just don't get something about permanent magnets.
A magnet exerts force, no?
Exerting force requires energy, no?
Where is the energy in a magnet? How is it obtained, stored, replenished?
Re: (Score:2, Insightful)
Not quite true - the moon doesn't orbit in a perfect circle, so it moves nearer and further away from Earth, speeding up and slowing down in the process, and so there is in fact a cyclic energy transformation between kinetic energy and potential energy. The overall energy though remains constant though.
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Okay, fair enough, but that energy transfer is nigh imperceptible compared to the changes over the course of every month.
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Oh? Please correct me then.
Re: Question for the Physicists. (Score:4, Interesting)
I was referring, badly, to motors using permanent magnets in the stator or armature, as opposed to those based entirely on electromagnets.
Actually though, you can make temporarily "perpetual motion" magnetic motors that draw power entirely from draining the energy stored in the magnets - for example, picture the situation where magnets on the rim of a wheel are attracted to a stationary magnet nearby. Then, roughly at the point of closest approach, the rim magnets pass behind some form of shielding so that there is no symmetrical force required for them to be moved away again. Unlike gravity (so far as we know) magnetic fields can be blocked, and so the rim magnets will perpetually "fall" towards the stationary one until the magnetic field is drained. You can do something similar with electrostatics as well, and many people have convinced themselves they've managed to create a perpetual motion machine that way.
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My understanding, probably wrong.
Yes. Due to interactions with other magnetic objects.
Yes.
Nowhere, the energy comes from external sources - a potential energy between two magnetic objects have to be in place for there to be any force. By magnetizing with an external magnetic field, in the electron spin of the magnet atoms, it isn't.
Re: (Score:2, Informative)
No, this is an elemental misunderstanding. Magnetism is inherent in the makeup of atoms, and thus of magnetic materials. Electrons have a negative charge and protons have a positive charge. As per Maxwell and the theory of Electromagnetism, electricity and magnetism are permanently and inextricably intertwined.
OK, so the "force" a magnet exerts is always sourced from outside the magnet itself. Therefore looking for an energy source inside the magnet is hopeless and useless; there is no internal energy s
Re:Question for the Physicists. (Score:5, Informative)
Exerting force requires energy, no?
No. A force does not require energy. Only moving against a force requires energy. E=F*D. A newton is force, but a newton-meter is energy. So the magnet on your refrigerator does not use energy, but energy is required to pull it off.
How is it obtained, stored, replenished?
Here is a really cool fact that you can use to impress chicks at cocktail parties: A magnetic force and an electrical force are the SAME THING. The only difference is your inertial frame of reference. Let's say you have two parallel copper wires with current flowing through them. The negative charge in the electrons and the positive charge in the copper nuclei should cancel each other out, and there should be no force between them. BUT THERE IS. This is magnetism. But it is really just plain only electrical attraction because the electrons are moving, so their inertial reference frame is different from the reference frame of the copper nuclei. A moving reference frame has a Lorentz contraction, so the copper nuclei "see" more electrons per length of wire, resulting in an attraction.
Re:Question for the Physicists. (Score:4, Interesting)
Here is a really cool fact that you can use to impress chicks at cocktail parties: A magnetic force and an electrical force are the SAME THING. The only difference is your inertial frame of reference. Let's say you have two parallel copper wires with current flowing through them. The negative charge in the electrons and the positive charge in the copper nuclei should cancel each other out, and there should be no force between them. BUT THERE IS. This is magnetism. But it is really just plain only electrical attraction because the electrons are moving, so their inertial reference frame is different from the reference frame of the copper nuclei. A moving reference frame has a Lorentz contraction, so the copper nuclei "see" more electrons per length of wire, resulting in an attraction.
No. Magnetic and electrical force and energy aren't exactly "the same thing". The magnetic and electric field are both components of the second rank field strength tensor, the Lorentz force in electromagnetic theory is not just the Lorentz transform of the Coulomb force, and magnetic and electric field energies are independently summed when assembling the total electromagnetic field energy density. Finally, good luck describing electron spin and the resultant intrinsic magnetic dipole moment in terms of a Lorentz transformation of the bare Coulomb field of the (point) charge -- there is no rotating frame or mass moving around mass.
There are basically two different ways to discuss them. One way is to stop talking about electric and magnetic fields independently at all and only work with the electromagnetic field (strength tensor) where the electric and magnetic components are NOT THE SAME and do NOT HAVE THE SAME SYMMETRY. The other way is to pretend (as most intro books do, because usually it works pretty well if you're considering low velocities and coarse-grain-averaged "smooth" charge/current densities) that E and B are ordinary vectors and write down Maxwell's equations. There are FOUR of them -- two if you go with the covariant field strength tensor formulation, and you cannot write them all down in terms of a single vector field (or the resultant force).
F_e = qE (F, E vectors)
F_b = q v x B (F, v, B vectors)
The electrostatic force obeys Newton's third law. The magnetic force (with the cross product) does not,. and one has to work very hard indeed to find the missing energy and momentum in the electromagnetic field when two charged particles interact in the general case.
Sadly, I haven't found that knowing graduate level electrodynamics well enough to teach it impresses chicks at cocktail parties.
Re: (Score:2)
I just don't get something about permanent magnets.
A magnet exerts force, no?
Exerting force requires energy, no?
Where is the energy in a magnet? How is it obtained, stored, replenished?
Magnets have a potential energy relative to a magnetic sample at any distance away, but the attraction falls off steeply, so you have to get close for the attraction to matter.
Once you get close, the magnet's pull will be felt, and the object will be attracted to the magnet. Let it move closer (It's on a string), and potential energy between the pair is reduced. To reverse it, just pull the string, which takes force-over-distance, and so you have invested energy to pull the little sample away. Energy is
Re:Question for the Physicists. (Score:5, Interesting)
These two new magnets are unlikely to replace the current champion (neodymium-iron-boron), or be particularly useful as permanent magnets at all. The reason is that the researchers only calculated the moment and Curie temperature. A good permanent magnet should also have a high magnetic anisotropy energy (MAE) as well. The Heusler alloys are predominantly cubic and so have a very low MAE.
How do I know this? We just spent three years doing exactly the same thing: spending thousands of CPU hours trying to find a good magnet among the Heuslers. All to no avail.
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Re: Question for the Physicists. (Score:2)
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No, magnetism isn't a force. It's a field. Much like a gravitational field - a distortion of the continuum. Magnetic force is what you get when two such distortions interact, much as gravitational force comes from the interactions of 2 objects with masses. There is potential energy, but until something moves, it's not "real" energy.
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A permanent magnet creates a static magnetic field, which can exert forces against moving or spinning charges.
> Exerting force requires energy, no?
What do mean by 'exerting'? Generally the answer is 'no'. Magnetic fields will bend the motion of charged particles.
> Where is the energy in a magnet?
A magnetic field has an energy density everywhere in space proportional to the square of the field strength.
Where did it come from in a permanent magnet? It happens that e
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A magnet exerts force e.g. on another magnet. But exerting force doesn't require energy as long as nothing moves. Work (W) is force (F) times distance (s) (in direction of the force) W=F*s, so as long as s=0 no work is done, no Energy needed.
Imagine the magnetic attraction replaced by a (extended) spring between the two metal parts. As long as nothing moves no energy needs to be replenished in the spring. If the metal parts are allowed to move closer energy is transferred from the spring to those parts (or
Doesn't Matter (Score:2)
"It doesn't really matter if either of these new magnets proves useful in the future. The ability to rapidly predict their existence is a major coup and will be invaluable to scientists making drinking wagers moving forward."
fixed that
Which supercomputer? (Score:5, Interesting)
TFA seems to leave out a lot of important geeky details. Like which supercomputer was used? How many hours of CPU (or maybe GPU?) time was used? Since they were running hundreds of models in parallel, why did they need a supercomputer at all? Wouldn't it have been more cost effective to rent compute servers in the cloud?
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They work inside cloud computers processors, apparently.
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Re:Which supercomputer? (Score:5, Interesting)
Rare-Earths aren't rare! (Score:3)
... rare-earth materials, which are both expensive and difficult to acquire."
or
http://www.bbc.com/news/magazine-26687605 (amongst others) that claim Rare-Earths are not rare and by extension not necessarily expensive or even very difficult to acquire.
Which is it then? Who should we believe?
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My understanding was that they were cheap and plentiful from China, but lately they've been hoarding for themselves.
The US has a significant of places where rare earths could be mined. The only problem is inertia from the long permitting process required to get a new mine going.
Re: Rare-Earths aren't rare! (Score:2)
Re:Rare-Earths aren't rare! (Score:5, Informative)
Not rare but they produce a ton of toxic waste being processed. It all went to China because they could do it cheaper and eat the toxic waste, too.
When China were embargoing exports (or talking about it) there was talk of granting exceptions to a closed mine in California to re-open as a strategic hedge.
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Rare earth mining does not produce toxic waste.
Why would it?
Basically you are just pit mining salts or digging out stones.
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Not rare but they produce a ton of toxic waste being processed. It all went to China because they could do it cheaper and eat the toxic waste, too.
A lot of that "waste" is thorium which I assume China is stockpiling.
When China were embargoing exports (or talking about it) there was talk of granting exceptions to a closed mine in California to re-open as a strategic hedge.
I thought that Mountain Pass mine should have been re-opened for several years but it seems the owner Molycorp was still in bankruptcy as of last fall ; hope the waste is being handled in a more environmentally friendly manner than before the closure.
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They are not rare.
And so cheap right now that plenty of mines in the americas are closed.
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And so cheap right now that plenty of mines in the americas are closed.
They are only cheap when you shit up the planet with no remorse, which is why they are coming out of China. But anyone buying them is funding the shitting up of the planet.
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The Chinese mine them in deserts. ... how much can you shit up there?
Wow
Mining Rare Earth minerals is just producing a lot of sand. And if you refine them in place a lot of salts.
Who cares about that? Most of the 'waste' stuff can be sold anyway.
You are smarter than most americans, why don't you read an article about it?
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and while it is true that the rare earths are actually pretty easy to find, the natural concentrations tend to be quite low, making it not commercially viable in most places.
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I predict the existence of new magnets by looking for advertising attached to a relatively thick but flexible rubbery base.
That's not all their supercomputers discovered! (Score:1, Funny)
Duke University's Gender Studies Department used the supercomputer to discover two new genders previously unknown to gender scientists. And in a complementary study, their English Department is planning to research possible new pronouns. Go Blue Devil Supercomputer!
Three videos tried to play at the same time... (Score:2)
on that no rare earth materials page. One I understand. But three?! Cacaphony of GTFO no matter how good of a read the article may have been.
Talking about rare (Score:3)
One of the magnetic (actually anti-ferromagnetic) compounds discovered was Mn2PtPd. Pt and Pd are two orders of magnitude more rare than the "relatively common" rare earths...
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Yes, that would be the reason why they said that only one of the two magnets is particularly "interesting".
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Yeah, most "rare earth" metals are far from rare, and often not that expensive, as there are deposits all over the world. One of the difficulties is that China had a huge supply and was dumping them on the market to gain global share and drive other mines to close down (reducing competitors and allowing them to raise the price). That is, of course, until they became a manufacturing powerhouse and realized they should be keeping those elements in-country to bolster their total manufacturing chain. Then, of c
This is not Design, dammit (Score:1)
The success marks a new era for the large-scale design of new magnetic materials
No, it doesn't. This is screening, and regardless of how much those in the field of drug "design" and materials "design" use those words, it's not Design, and it's not Engineering. It's Discovery, and it's great that physics and computation have gotten to the point where we can actually discover useful things in silico much faster than at the bench. But engineering requires an understanding of the underlying relationship between materials composition and desired quantitative property, and that is largely st
What is rare about rare earth? (Score:2)