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AnonTechie writes:

An experiment conducted by Princeton researchers has revealed an unlikely behavior in a class of materials called frustrated magnets (http://en.wikipedia.org/wiki/Geometrical_frustration), addressing a long-debated question about the nature of these discontented quantum materials.

The researchers tested the frustrated magnets—so-named because they should be magnetic at low temperatures but aren't—to see if they exhibit a behavior called the Hall Effect. When a magnetic field is applied to an electric current flowing in a conductor such as a copper ribbon, the current deflects to one side of the ribbon. This deflection, first observed in 1879 by E.H. Hall, is used today in sensors for devices such as computer printers and automobile anti-lock braking systems.

Because the Hall Effect happens in charge-carrying particles, most physicists thought it would be impossible to see such behavior in non-charged, or neutral, particles like those in frustrated magnets. "To talk about the Hall Effect for neutral particles is an oxymoron, a crazy idea," said N. Phuan Ong, Princeton's Eugene Higgins Professor of Physics.

Nevertheless, some theorists speculated that the neutral particles in frustrated magnets might bend to the Hall rule under extremely cold conditions, near absolute zero, where particles behave according to the laws of quantum mechanics rather than the classical physical laws we observe in our everyday world. Harnessing quantum behavior could enable game-changing innovations in computing and electronic devices. Ong and colleague Robert Cava, Princeton's Russell Wellman Moore Professor of Chemistry, and their graduate students Max Hirschberger and Jason Krizan decided to see if they could settle the debate and demonstrate conclusively that the Hall Effect exists for frustrated magnets.

[Abstract]: http://www.sciencemag.org/content/348/6230/106.short

[Source]: http://blogs.princeton.edu/research/2015/04/03/frustrated-magnets-new-experiment-reveals-clues-to-their-discontent/

Introduction to frustrated magnets [PDF Presentation]: http://www.lpt.ups-tlse.fr/IMG/pdf_Lecture5-frustrated_magnets-LesHouches2011.pdf