Magnetic RAMs

Magnetic random-access memory (MRAM) is a new type of computer memory. MRAMs retain their state of magnetization even with the power off, but unlike present forms of nonvolatile memory, they have switching and rewritability rates that challenge (are faster than) those of conventional RAM. In today s read heads as well as those of MRAMs, key features are made of ferromagnetic metallic alloys. Such metal-based devices make up the first—and most mature—of the various categories of spintronics. 

Key to abbreviations MW = microwave NS = neutron scattering IR = infrared T = nuclear magnetic resonance Ram = Raman v = vapor phase 1 = liquids s = solid. thermodynamic NMR =... 

A number of alternative methods are available for determining /ram-isomers, including spectroscopy, both infrared (IR) and Raman, and nuclear magnetic resonance (NMR) (Firestone and Sheppard, 1992). 

Ram, P., and J.H. Prestegard (1988) Magnetic field induced ordering of bile salt/phospholipid micelles new media for NMR structural investigations. Biochim. Biophys. Acta 940, 289-294. 

Scheinfein MR, Schmidt KE, Heim KR, Hembree GG (1996) Magnetic order in two-dimensional arrays of nanometer-sized snperpaiamagnets. Phys Rev Lett 76 1541-1544 Schmidt H, Ram RJ (2001) Coherent magnetization reversal of nanoparticles with crystal and shape anisotropy. J Appl Phys 89 507-513... 

For the observation of h the manometer tubes shown in fig. 1 were employed. The tubes were mounted on a p- P transparent ram.-scale illuminated from be-] hind. During each of the original experiments ] the magnetic field intensity H was kept con-] stant and the flow adjusted for a series of... 

The magnetic properties of most of the amorphous rare earth-nickel compounds are similar to those of alloys in which the rare earths are combined with nonmagnetic metals since the Ni atoms do not carry a magnetic moment in these alloys for all but the highest Ni concentration. For alloys with a rare earth component having non-zero orbital moment the so-called RAM model proposed by Harris et al. (1973)... 

Typically, practical graded dielectric RAMs are constructed of discrete layers, with properties changing from layer to layer. A technique for reducing the reflection from the front face of a flat absorber is to use semiconductive foams obtained by impregnation with carbon or dispersion of carbon fibrils. A careful combination of these foams with an internal magnetic layer of the iron-filled elastomer type leads to wide bandwidth materials which can operate readily between 4 and 18 GHz [29] as shown in Figure 8.3,... 

Mardor Y, Roth Y, Lidar Z, Jonas T, Pfeffer R, Maier SE, Faibel M, Nass D, Hadani M, Orenstein A, Cohen JS, Ram Z. Monitoring response to convection-enhanced taxol delivery in brain tumor patients using diffusion-weighted magnetic resonance imaging. Cancer Res 2001 61 4971-4973. 

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