Search

Coastal and marine ecosystems provide a host of services that are of vital importance to human well-being. We estimate the values of several provisioning, regulating, and recreational services using a combination of valuation methods. We find that the total value of these services in India was approximately ₹1.9 trillion (or US$0.11 trillion in purchase price parity [PPP] terms) in 2012–13, which constitutes about 2.4% of India’s net national product that year. Recreational services account for the largest share (45%), followed by regulating services (35%) and provisioning services (20%). These estimates do not include all the services provided by coastal and marine ecosystems; therefore, our estimates should be treated as a conservative underestimate of their total economic value. To the best of our knowledge, this is the first such attempt at the national level in India.

Thin films of the spin-crossover (SCO) molecule Fe{[Me2Pyrz]3BH}2 (Fe-pyrz) were sublimed on Si/SiO2 and quartz substrates, and their properties investigated by X-ray absorption and photoemission spectroscopies, optical absorption, atomic force microscopy, and superconducting quantum interference device. Contrary to the previously studied Fe(phen)2(NCS)2, the films are not smooth but granular. The thin films qualitatively retain the typical SCO properties of the powder sample (SCO, thermal hysteresis, soft X-ray induced excited spin-state trapping, and light induced excited spin-state trapping) but present intriguing variations even in micrometer-thick films: the transition temperature decreases when the thickness is decreased, and the hysteresis is affected. We explain this behavior in the light of recent studies focusing on the role of surface energy in the thermodynamics of the spin transition in nano-structures. In the high-spin state at room temperature, the films have a large optical gap (~5 eV), decreasing at thickness below 50 nm, possibly due to film morphology. [ABSTRACT FROM AUTHOR]

A combined atomic force microscopy/scanning tunneling microscope has been used to map the tunnel current flowing through metal/oxide stacks, in order to obtain a nanoscopic insight into the origins of fluctuations. Total conductance of imperfect metal/oxide junctions is found to be dominated by very few sites, enabling the sample-to-sample conductance fluctuations to be relating to slight variations of tunnel barrier parameters.

Recent irradiation experiments on magnetic tunnel junctions (MTJ) using either light (C, O) or heavy (Ni) ion beams with energies in the range of 10 MeV/A are presented. The effects observed are small in amplitude but irreversible, and seem to depend upon the nature of the junctions.

We report the temperature dependent far-infrared spectrum of ultra-thin films of polyethylene oxide (PEO). Using the orientational specificity of infrared and far-infrared reflection–absorption spectroscopy and in-situ recrystallization, we find that during spin coating the PEO helices are initially in the plane of the film, but on crystallization reorient to be normal to the substrate. A splitting of the C–O torsional mode near 109 cm-1 is identified as arising from a distortion of the normal helical structure of PEO. Comparison with transmission spectra of cast films demonstrates the value of far-infrared reflection–absorption spectroscopy (FIRRAS) in the study of crystalline polymers in the far infrared. [ABSTRACT FROM AUTHOR]

A powerful technique for controlling the oxidation of ultrathin metallic layers is described. This technique consists of depositing the metallic layer to be oxidized on top of the soft magnetic layer of a bottom spin valve.

The present work reports on the inelastic, spin-dependent tunneling in magnetic junctions with AlOx barrier and Co50Fe50 ferromagnetic (FM) electrodes. The identification of the transport inelastic channels is possible through their distinctive temperature dependencies. For the observed temperature behavior of the magnetotransport properties of the junctions, two spin-dependent, inelastic mechanisms are proposed: assisted tunneling due to interfacial (a) magnons and (b) metallic phonons. Their relative contributions are closely linked to the microstructural properties of the FM metal/oxide interfaces, related to the plasma oxidation of the tunnel barrier and to thermal annealing. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A first experimental evidence of a significant tunneling magnetoresistance signal of about 5% at 300 K for a magnetic tunnel junction consisting of hard and soft magnetic layers separated by a 2 nm ZnS semiconducting barrier is reported. The samples have been grown by sputtering on Si(111) substrate at room temperature and have the following structure: Fe[sub 6 nm]Cu[sub 30 nm]CoFe[sub 1.8 nm]Ru[sub 0.8 nm]CoFe[sub 3 nm]ZnS[sub x]CoFe[sub 1 nm]Fe[sub 4 nm]Cu[sub 10 nm]Ru[sub 3 nm]. The hard magnetic bottom electrode consists of the artificial antiferromagnetic structure in which the rigidity is ensured by the antiferromagnetic exchange coupling between two FeCo layers through a Ru spacer layer. Barrier impedance scanning microscope (BISM) measurements reveal a good homogeneity of the barrier thickness. Electric transport measurements over square tunnel elements with lateral sizes between 3 and 100 μm, exhibit a typical tunnel current-voltage variations and tunnel res! istance of 2-3 kΩ μm2 with small variations which never exceed a factor of 2, which is in good agreement with the BISM results. This good reproducibility of the junctions is very promising for MRAMs and transistors applications. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

In this work we study properties of very thin insulating Al oxide films, used as barriers in magnetic tunnel junctions. For the small barrier thicknesses required for technological applications (∼10 Å), the presence of pinholes (direct contact between the ferromagnetic metals through the barrier), or oxidation inhomogeneities, are the major factors for vanishing of the tunnel magnetoresistance effect. We have produced and characterized very thin, pinhole-free Al oxide layers, incorporated in magnetic tunnel junctions. The transport properties of the different barriers were analyzed by barrier impedance scanning microscopy and were correlated with the magnetotransport properties of the patterned microsized junctions. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Magnetostatic interactions between the soft and the hard magnetic electrodes in magnetic tunnel junctions (MTJs) using artificial ferrimagnets (AFis) are analyzed. We attribute these interactions to the dispersion fields associated to magnetic inhomogeneities arising from domain walls due to local anisotropic ordering. These magnetostatic interactions can be controlled by adjusting the net magnetic moment of the AFi to optimize the magnetotransport response of the MTJ devices.© 2001 American Institute of Physics. Magnetostatic interactions between the soft and the hard magnetic electrodes in magnetic tunnel junctions (MTJs) using artificial ferrimagnets (AFis) are analyzed. We attribute these interactions to the dispersion fields associated to magnetic inhomogeneities arising from domain walls due to local anisotropic ordering. These magnetostatic interactions can be controlled by adjusting the net magnetic moment of the AFi to optimize the magnetotransport respons! e of the MTJ devices.© 2001 American Institute of Physics. Magnetostatic interactions between the soft and the hard magnetic electrodes in magnetic tunnel junctions (MTJs) using artificial ferrimagnets (AFis) are analyzed. We attribute these interactions to the dispersion fields associated to magnetic inhomogeneities arising from domain walls due to local anisotropic ordering. These magnetostatic interactions can be controlled by adjusting the net magnetic moment of the AFi to optimize the magnetotransport response of the MTJ devices.© 2001 American Institute of Physics. Magnetostatic interactions between the soft and the hard magnetic electrodes in magnetic tunnel junctions (MTJs) using artificial ferrimagnets (AFis) are analyzed. We attribute these interactions to the dispersion fields associated to magnetic inhomogeneities arising from domain walls due to local anisotropic ordering. These magnetostatic interactions can be controlled by adjusting the net magnetic! moment of the... [ABSTRACT FROM AUTHOR]

The impact of the micromagnetic configuration within the ferromagnetic layers on transport properties of hard/soft magnetic tunnel junctions is presented. An artificial ferrimagnetic (AFi) trilayer structure is used as a magnetically hard subsystem. Fluctuations in magnetization in the AFi affect the resistance of the tunnel junctions and are fully reflected in the shape and amplitude of the tunnel magnetoresistance signal. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Magnetic tunnel junctions have been fabricated, that use Co/Ru/Co and Co/Ru/CoFe artificial ferrimagnet (AFi) systems as hard magnetic electrodes. The ∼22% tunnel magnetoresistance signal obtained, at room temperature, for junctions with Co/Ru/Co was increased to ∼30% by taking advantage of the higher spin polarization of CoFe in contact with the barrier. Along with this improvement, a different reversal behavior for the AFi was obtained. Together with the enhanced thermal stability, up to 350 °C, of the junctions involving the Co/Ru/CoFe system potential use as magnetic sensors is discussed. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]