Well, this is interesting. I was just talking with my daughter about magnetic monopoles the other evening. Really. Seriously. I was.
Quit looking at me that way. She seemed interested…
Magnetic monopoles (objects that have magnetic field but with only a south or a north pole – unlike the typical bar magnets we played with as kids that had both) were an area of intense interest and research in the late ’70s and ’80s. When I was in grad school we were constantly hearing reports that this or that theorist had finally figured out where we would observe them. And how the standard models of particle physics required them. And for all that, no one has ever verifiably observed them.
So when I saw this article today entitled “Magnetic monopoles detected in a real magnet for the first time” and having just mentioned this fruitless search to my daughter, I immediately read the report:
“Jonathan Morris, Alan Tennant and colleagues (HZB) undertook a neutron scattering experiment at the Berlin research reactor. The material under investigation was a single crystal of Dysprosium Titanate. This material crystallizes in a quite remarkable geometry, the so called pyrochlore-lattice. With the help of neutron scattering Morris and Tennant show that the magnetic moments inside the material had reorganised into so-called „Spin-Spaghetti’. This name comes from the ordering of the dipoles themselves, such that a network of contorted tubes (Strings) develops, through which magnetic flux is transported. These can be made visible by their interaction with the neutrons which themselves carry a magnetic moment. Thus the neutrons scatter as a reciprocal representation of the Strings.
During the neutron scattering measurements a magnetic field was applied to the crystal by the researchers. With this field they could influence the symmetry and orientation of the strings. Thereby it was possible to reduce the density of the string networks and promote the monopole dissociation. As a result, at temperatures from 0.6 to 2 Kelvin, the strings are visible and have magnetic monopoles at their ends.
In this work the researchers, for the first time, attest that monopoles exist as emergent states of matter, i.e. they emerge from special arrangements of dipoles and are completely different from the constituents of the material. However, alongside this fundamental knowledge, Jonathan Morris explains the further meaning of the results: „We are writing about new, fundamental properties of matter. These properties are generally valid for materials with the same topology, that is for magnetic moments on the pyrochlore lattice. For the development of new technologies this can have big implications. Above all it signifies the first time fractionalisation in three dimensions is observed.'”
Read the full article here.
So this isn’t the mythical jabber-wocky like particle monopole. This appears instead to be a structural or phase based monopole. Which is really interesting – and will finally allow us to change the pesky zero in the second of Maxwell’s equations to something more like the charge density of the first equation. Which makes many theorists very happy. (We love symmetry.)
But, there’s still the question of whether or not the single particle monopole exists. (Assuming that this report is in fact verified in the first place.)