RARE-EARTH DOPING USED TO CONTROL HIGH-SPEED DYNAMICS OF MAGNETIC DATA STORAGE COMPONENTS.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. staff have explored the use of rare-earth dopants to control the high-speed dynamics in magnetic thin films used in magnetic recording heads and magnetic random access memory (MRAM (Magnetic RAM) A non-volatile, random access memory technology that is designed to initially replace flash memory and, potentially, DRAM memory. MRAM uses magnetic, thin film elements on a silicon substrate that can be built on the same chip with the logic circuits. ). They discovered that a few percent of Tb dopants in Ni-Fe films can dramatically increase the magnetic damping without substantially changing the other magnetic properties. The films can be engineered to be underdamped, critically damped, or overdamped by varying the dopant dopant Any impurity added to a semiconductor to modify its electrical conductivity. The most common semiconductors, silicon and germanium, form crystalline lattices in which each atom shares electrons with four neighbours (see bonding). concentration from 0% to 4%. High-speed measurements were made at frequencies up to 6 GHz using a pulsed inductive technique. Rare earths have long been known to increase magnetic damping in ferrite fer·rite n. 1. Any of a group of nonmetallic, ceramiclike, usually ferromagnetic compounds of ferric oxide with other oxides, especially such a compound characterized by extremely high electrical resistivity and used in computer memory materials used in microwave devices. For microwave applications, damping is undesirable, and efforts have concentrated on eliminating rare-earth impurities. However, for magnetic data storage applications, critically damped behavior is desirable to prevent ringing and magnetic turbulence when magnetic elements (Chem. Physics) Those elements, as iron, nickel, cobalt, chromium, manganese, etc., which are capable or becoming magnetic. (Physics) In respect to terrestrial magnetism, the declination, inclination, and intensity See under Element. See also: Magnetic Magnetic Magnetic are rotated or switched. For instance, a typical "spin-valve" read sensor, in response to a 250 ps pulsed field from a magnetic bit, will ring for approximately 2 ns after the applied bit field. Similarly, when an MRAM element is switched, the magnetic energy will cause the element to oscillate To swing back and forth between the minimum and maximum values. An oscillation is one cycle, typically one complete wave in an alternating frequency. or break up into a disordered high-temperature magnetic state. The switching properties of the element will be dramatically altered until the magnetic energy is removed from the system. This can lead to undesirable switching in MRAM arrays if the clock speeds are faster than the magnetic cooling rate. Further temperature-dependent measurements and characterization of films doped with different rare earths indicate that the increased damping is due to local lattice distortions at the rare-earth sites due to anisotropic Refers to properties that differ based on the direction that is measured. For example, an anisotropic antenna is a directional antenna; the power level is not the same in all directions. Contrast with isotropic. orbitals that are strongly coupled to the film magnetization. The ability to engineer the high-speed dynamical properties of magnetic systems will become critical in the next few years when both magnetic recording and MRAM operation will be pushed into the gigahertz regime. |
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