SUPERCOOLING AND SUPERHEATING OF VORTEX MATTER.The behavior of quantized quan·tize tr.v. quan·tized, quan·tiz·ing, quan·tiz·es Physics 1. To limit the possible values of (a magnitude or quantity) to a discrete set of values by quantum mechanical rules. 2. flux lines in type-II superconductors is of critical importance in a variety of high-current applications anticipated for "high temperature" superconductors, such as magnets for medical imaging and power transmission cables. These vortex systems also provide a prototypical system for the study of fundamental problems in phase transitions and melting phenomena. Unfortunately, vortex structures have been difficult to investigate in detail in the cuprate materials because of the intrinsically short superconducting length scales and because of materials quality problems. A current subject of wide interest concerns the possibility of a solid-liquid transition of vortex matter and its relation to the dramatic transport anomaly in superconductors known as the peak effect, in which the critical current exhibits a maximum rather than decreasing monotonically with increasing temperature. Researchers at Brown University and the NIST (National Institute of Standards & Technology, Washington, DC, www.nist.gov) The standards-defining agency of the U.S. government, formerly the National Bureau of Standards. It is one of three agencies that fall under the Technology Administration (www.technology. Center for Neutron Research have now carried out small angle n eutron scattering measurements combined with in-situ ac magnetic measurements, on a high-quality niobium niobium (nīō`bēəm), metallic chemical element; symbol Nb; at. no. 41; at. wt. 92.9064; m.p. about 2,468°C;; b.p. 4,742°C;; sp. gr. 8.57 at 20°C;; valence +2, +3, +4, or +5. crystal where these experimental difficulties are averted. They report the first structural evidence for a first-order vortex solid-liquid transition associated with the peak effect. In particular, superheating
In physics, superheating (sometimes referred to as boiling retardation, or boiling delay of the vortex solid and supercooling Supercooling is the process of chilling a liquid below its freezing point, without it becoming solid. Description A liquid below its freezing point will crystallize in the presence of a seed crystal or nucleus around which a crystal structure can form. of the vortex liquid have been observed directly for the first time. This is an important result for assessing future technological applications, since there is a definite limit, by virtue of being a first-order transition, to which the materials properties This is a list of materials properties. A materials property is an intensive, often quantitative property of a material, usually with a unit that may be used as a metric of value to compare the benefits of one material versus another to aid in materials selection. can be tailored to achieve the highest critical currents. These results also open up the possibility to experimentally test the fundamental theoretical ideas of melting in bulk solids. For example, in conventional solids surface melting masks any superheating effects, while a superheated su·per·heat tr.v. su·per·heat·ed, su·per·heat·ing, su·per·heats 1. To heat excessively; overheat. 2. vortex lattice is stable for hours, but can be melted by applying a small perturbing ac magnetic field. |
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