Quantum tunneling in magnetic tunneling junctions

This paper reports on the study of ferromagnetic tunneling junctions produced by magnetron sputtering technique and deposited under oxidation conditions that lead to low potential barrier height, low asymmetrical barrier and quantum tunneling as the charge transport mechanism. The exponential growth of the effective area-resistance product with the effective barrier thickness, and the concentration of the tunnel current in small areas of the junctions, were identified by fitting room temperature I-V curves, for each individual sample, with either Simmons’ [J. Appl. Phys. 34, 1793 (1963); 35, 2655 (1964); 34, 2581 (1963)] or Chow’s [J. Appl. Phys. 36, 559 (1965)] model. This result suggests the presence of effective tunneling areas or hot spots, leading to a non-uniform current distribution and showing quantum tunneling as the charge transport mechanism. This mechanism, is also, verified through I-T curves

Magnetostriction in ar/sup +/ implanted and annealed co/pd multilayers

Magnetostriction curves with (111) textured polycrystalline Co/Pd multilayers, as deposited or submitted to ArS ion implantation or thermal annealing, are presented and discussed. Both treatments, while promoting intermixing among CO and Pd atoms, induce an increase in the saturation magnetostriction values. The evolution of the engineering curves, however, are different due to different structural modifications promoted by the two treatments

Correlation between giant magnetoresistence and magnetic interactions in a Co/Ag multilayed/granular system

Magnetizing, demagnetizing, and remanent magnetization curves for [Co (12 Å)/Ag(60 Å)]x15 multilayered/granular films thermally treated have been measured. The changes of the giant magnetoresistance and the interaction effects have been explained as a result of the structural, morphological, and magnetic evolution of the samples as a function of the thermal treatment. It has been inferred that for samples annealed at temperatures lower than 360 °C, the changes of the giant magnetoresistance come from the misalignment of the magnetic moments of the Co particles formed during annealing. A strong correlation between the giant magnetoresistance and the magnetic interaction effects has been found for samples annealed at temperatures higher than 360 °C: the giant magnetoresistance is degraded as the demagnetizing interparticle interactions are increased

Correlation between giant magnetoresistence and magnetic interactions in a Co/Ag multilayed/granular system

Magnetizing, demagnetizing, and remanent magnetization curves for [Co (12 Å)/Ag(60 Å)]x15 multilayered/granular films thermally treated have been measured. The changes of the giant magnetoresistance and the interaction effects have been explained as a result of the structural, morphological, and magnetic evolution of the samples as a function of the thermal treatment. It has been inferred that for samples annealed at temperatures lower than 360 °C, the changes of the giant magnetoresistance come from the misalignment of the magnetic moments of the Co particles formed during annealing. A strong correlation between the giant magnetoresistance and the magnetic interaction effects has been found for samples annealed at temperatures higher than 360 °C: the giant magnetoresistance is degraded as the demagnetizing interparticle interactions are increased

Effects of Ar-ion implantation and annealing on structural and magnetic properties of Co/Pd multilayers

The contrasting effects of ion implantation and thermal annealing on structural and magnetic properties of Co/Pd multilayers have been studied. Ion implantation causes local damage to the multilayers, resulting in enhanced magnetization due to the polarization of the neighboring Pd. Thermal annealing generates massive interdiffusion across the interfaces into the formation of Co-Pd alloys with a lower magnetization. Effects on coercivity and remanence have also been studied

Quantum tunneling in magnetic tunneling junctions

This paper reports on the study of ferromagnetic tunneling junctions produced by magnetron sputtering technique and deposited under oxidation conditions that lead to low potential barrier height, low asymmetrical barrier and quantum tunneling as the charge transport mechanism. The exponential growth of the effective area-resistance product with the effective barrier thickness, and the concentration of the tunnel current in small areas of the junctions, were identified by fitting room temperature I-V curves, for each individual sample, with either Simmons’ [J. Appl. Phys. 34, 1793 (1963); 35, 2655 (1964); 34, 2581 (1963)] or Chow’s [J. Appl. Phys. 36, 559 (1965)] model. This result suggests the presence of effective tunneling areas or hot spots, leading to a non-uniform current distribution and showing quantum tunneling as the charge transport mechanism. This mechanism, is also, verified through I-T curves

El Eco de Santiago : diario independiente: Año VIII Número 1605 - 1903 Septiembre 02

This paper reports on the study of deposited (Ni81Fe19/AlOx /Co) magnetic tunnel junctions by magnetron sputtering, with the insulating layer obtained by plasma oxidation of Al. Concentration of the tunnel current in small areas of the junctions and low potential barrier heights were identified by fitting, for each individual sample, the room temperature I-V curves with either Simmons’ [J. Appl. Phys. 34, 1793 1963 ; 35, 2655 (1964) ; 34, 2581 (1963)] or Chow’s [J. Appl. Phys. 36, 559 (1965)] model. A fast decrease of the tunnel magnetoresistance as a function of the bias voltage is observed, with an inversion of its signal above a critical value. The results are discussed in terms of the quantum coherence factor for low height insulating barriers

Structural and magnetic behavior of ar+-implanted co/pd multilayers : interfacial mixing

The magnetization behavior of Co/Pd multilayers has been analyzed as a function of the degree of interfacial mixing among the Co and Pd layers. Controlled atomic mixing was induced by low-dose and low-flux ion implantation and a follow-up of the structural status of the samples was made by simulation of the high-angle x-ray-diffraction data. Values of the saturation magnetization as a function of the broadness of Co concentration profile are presented and explained by a simple model based on the parameters obtained from the x-ray simulations