From UVaToday:

(A University of Virginia-led team) discovered that the magnetic effect of apparently all metamagnets is that it is non-linear. When these metamagnets are placed in an initial magnetic field and the field is doubled, they more than double in magnetic strength. This is significant because eventually scientists and engineers likely will harness this unique property for a variety of applications, including refrigeration.

"We found that this nonlinear property has the same quantitative behavior in all different types of metamagnets, which is the universal law," said Bellave Shivaram, a University of Virginia professor of physics who led the studies, which were conducted in his lab and using materials synthesized at Argonne National Laboratory in Illinois.

For more, see:
http://news.virginia.edu/content/newly-identified-universal-property-metamagnets-may-lead-everyday-uses
and:
http://scitation.aip.org/content/aip/journal/rsi/85/4/10.1063/1.4870796