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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 4924-4926 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This investigation has examined the use of the laminated antiferromagnet PtMn/IrMn to exchange bias spin valves in an attempt to combine the high exchange field and blocking temperature of PtMn with the good pinning profile of IrMn. The effect of varying the IrMn thickness was examined for top and bottom spin values exchange biased by CoFe20Å/IrMn/PtMn. For top spin valves, Hex rapidly decreases as IrMn thickness is increased, with the exchange pinning virtually disappearing by 20 Å. As the thickness continues to increase the pinning reappears, and by 40 Å of IrMn an exchange field of 500 Oe and coercivity of 100 Oe are observed. This exchange field is slightly higher than that observed for CoFe/IrMn40 spin valves (400 Oe as deposited, 470 Oe after annealing). For bottom spin valves the same trends are observed, although the pinning never completely disappears. Also, the exchange field of 600 Oe is lower than that obtained for IrMn (670 Oe), presumably due to the rougher interface of the PtMn underlayer. For both top and bottom spin valves the laminated antiferromagnet showed improvement in thermal stability compared to as deposited and annealed IrMn spin valves. © 2000 American Institute of Physics.
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 5726-5728 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This investigation focused on how spin-valve thermal stability is related to different antiferromagnetic materials: FeMn, IrMn, NiMn, PtMn, and PtPdMn. Measurements of the spin-valve exchange biasing field versus temperature show the following relationship in blocking temperatures: FeMn〈IrMn〈PtPdMn〈PtMn〈NiMn. Looking at the blocking temperature distributions, both FeMn and IrMn show sharp peaks, but at low temperatures (∼110 °C). In the case of the other materials, the distribution peaks at much higher temperature (〉250 °C), but are broader. Pinned angle rotation and giant magnetoresistance versus temperature measurements give the same thermal stability hierarchy, as well as providing information about interdiffusion in these spin-valves. For comparison, synthetic antiferromagnet spin-valves (based on IrMn and PtMn) were also measured. The synthetic structures did not show significantly different blocking temperatures or giant magnetoresistance temperature dependence than standard spin-valves. However, blocking temperature distribution and pinned layer rotation measurements showed improved stability for the synthetic structures, which may be attributed to the very thin effective pinned layer which results in high exchange biasing fields in these structures. © 2000 American Institute of Physics.
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 5741-5743 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: As recording densities increase, the sense layer (free layer) thickness in a recording head (whether spin-valve or otherwise) must also decrease so that the sense layer can be effectively saturated by the transitions on the media. However, in a traditional spin-valve structure, reducing the sense layer (free layer) thickness below ∼50 Å results in a rapid reduction in ΔR/R. One of the solutions for this is the spin-filter spin-valve, having a free layer composed of a very thin magnetic layer and an adjacent thin enhancing conduction layer. The advantage of the spin-filter spin-valve is high ΔR/R and easy control of the bias point while keeping the free layer very thin (10–30 Å). The present work reports the results on sputtered IrMn top and bottom spin-filter spin-valves. The data clearly show that ΔR/R has been significantly improved when reducing the free layer CoFe down to 10 Å. ΔR/R〉8.0% remains for free layer thickness between 10 and 20 Å using a Cu enhancing layer, while ΔR/R decreased rapidly to 4.0% with no Cu enhancing layer for the same free layer thickness range. An optimized ΔR/R of ∼10% was obtained for an enhancing layer of tCu∼13 Å, as a result of the balance between the increase in electron mean free path difference and current shunting through the very conducting enhancement layer. It was also found that the softness of the CoFe free layer was improved when sandwiched by Cu layers, showing similar soft properties and magnetostriction to conventional free layers. Such a soft, thin CoFe free layer is particularly attractive for high density (30–50 Gb/in2) read sensor applications. © 2000 American Institute of Physics.
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 6989-6991 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The present work is a comparative study of CoFe/IrMn exchange biased top, bottom, and dual spin valves. For as-deposited top spin valves the exchange bias energy Jk was determined to be 0.14 erg/cm2 for IrMn 50 Å. The exchange field (Hex) decreases rapidly upon heating, resulting in a blocking temperature (Tb) of 250 °C. For bottom IrMn based spin valves the exchange bias energy is much higher (Jk=0.28 erg/cm2) while ΔR/R (6.9%) is reduced with respect to top spin valves (〉8.0%). This is interpreted as showing that Hex is dominantly dependent on fcc(111) crystalline texture while ΔR/R is sensitive to both crystalline texture and interface roughness. Dual spin valves based on the above results showed two exchange loops due to the difference in the exchange bias energy between the top and bottom pinning layers. © 2000 American Institute of Physics.
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 5462-5464 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Films of Ni1−xZrx metallic glasses have been prepared by sputter deposition over the composition range 0.1〈x〈0.86. In this paper we present data on the composition and temperature dependencies of the resistivity and the Hall coefficient from 77 to 300 K. Where applicable, both the resistivity and the Hall coefficient closely follow the values reported for melt-spun glasses of the same composition. The Hall coefficient changes sign from positive to negative with decreasing x; for x〈0.4 it also becomes increasingly temperature dependent (dRH/dT〉0). Both the change in sign and the temperature dependence can be understood within the framework of an important extraordinary contribution to the Hall coefficient for these paramagnetic alloys.
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 6109-6111 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The antiferromagnetic alloy Pt20Pd30Mn50 has demonstrated a high exchange coupling field to a coupled NiFe film as well as high corrosion resistance, making it a promising candidate for use as the pinning layer of a spin valve. In this work we have investigated the magnetic and structural properties of spin-valve films exchange biased by CoFe/PtPdMn as compared to CoFe/IrMn spin valves. A spin-valve film structure of Ta50 Å/NiFe50 Å/CoFe20 Å/Cu28 Å/CoFe22 Å/PtPdMn300 Å/Ta50 Å annealed at 250 °C for 10 h showed a giant magnetoresistance of 6.5% with an exchange field of 680 Oe. The blocking temperature of this film is about 350 °C, compared to 250 °C for IrMn based spin valves. The remnant blocking temperature was also measured, and showed that for PtPdMn spin valves the exchange field was constant up to a temperature of 300 °C, in contrast to 180 °C for an IrMn spin valve. Structural ordering of the PtPdMn in a face-centered-tetragonal (fct) phase after annealing has been observed using x-ray diffraction and transmission electron microscopy. The x-ray diffraction data exhibits a strong face-centered-cubic (111) and fct (111) out-of-plane orientation for as-deposited and annealed samples. Transmission electron micrographs show a smooth interface between the PtPdMn and CoFe layers, columnar growth structure, and fct ordering of the PtPdMn. © 1999 American Institute of Physics.
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  • 7
    Publication Date: 2000-05-01
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
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  • 8
    Publication Date: 2000-05-01
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
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  • 9
    Publication Date: 2002-01-01
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
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  • 10
    Publication Date: 2002-01-01
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
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