A spin ice is a substance that is similar to water ice in that it can never be completely frozen. This is because it does not have a single minimal-energy state. A spin ice has "spin" degrees of freedom (i.e., it is a magnet), with frustrated interactions which prevent it freezing. It shows low-temperature properties – in particular residual entropy – closely related to those of crystalline water ice. The most prominent compounds with such properties are dysprosium titanate and holmium titanate. The magnetic ordering of a spin ice resembles the positional ordering of hydrogen atoms in conventional water ice.
Recent experiments have shown strong evidence for the existence of deconfined magnetic monopoles in these materials, with analogous properties to the hypothetical magnetic monopoles postulated to exist in the vacuum.
Read more about Spin Ice: Technical Description, Spin Ices and Magnetic Monopoles, See Also
Famous quotes containing the words spin and/or ice:
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—David Lehman (b. 1948)
“Every incident connected with the breaking up of the rivers and ponds and the settling of the weather is particularly interesting to us who live in a climate of so great extremes. When the warmer days come, they who dwell near the river hear the ice crack at night with a startling whoop as loud as artillery, as if its icy fetters were rent from end to end, and within a few days see it rapidly going out. So the alligator comes out of the mud with quakings of the earth.”
—Henry David Thoreau (1817–1862)