Search

The effect of field annealing on the magnetic tunnel junctions (MTJs) with an artificial antiferromagnetic layer is investigated. Samples, which were grown under the same condition, are annealed with low (200-Oe) and high (1-kOe) magnetic fields. The rotation of the pinned direction is observed for the sample annealed at high magnetic field without decrease of tunneling magnetoresistance by varying the applied field direction. This result provides a method to adjust the pinned direction of the MTJ, which may be critical in switching a magnetic RAM (MRAM) cell. Index Terms--Artificial anitferromagnetic (AAF) layer, field annealing, magnetic tunnel junction (MTJ), tunneling magnetoresistance (TMR).

The study of temperature dependence of tunneling magnetoresistance (TMR) for spin valve type double-barrier tunnel junctions (DBTJs) is discussed. The temperature dependence of TMR for DBTJs is found to be stronger than the temperature dependence of TMR for single-barrier tunnel junctions (SBTJs)

Theoretical analysis of weak localization for the three dimensional system presently does not include the case with strong scattering by local magnetic impurities. For paramagnetic [Fe.sub.0.33][Zr.sub.0.67] alloy, a composition just below the ferromagnetic phase boundary, the magnetic impurity scattering tune ([[Tau].sub.s]) is estimated to be comparable to the spin-orbit scattering time ([[Tau].sub.so]), but much less than the magnetic field dephasing time ([[Tau].sub.H]) or inelastic scattering time ([[Tau].sub.i]), so that the magnetic scattering occurs before the magnetic field dephasing does. When the local moments of magnetic impurities (in this case some of the Fe ions) do not interact with each other and their magnetization follows the Brillouin function, the magneto-resistance MR is proportional to [Mathematical Expression Omitted] for small (H/T), where [n.sub.s] is the density of local impurities of moment gS[[Mu].sub.B], and [Delta][Rho](H, T)/[[Rho].sup.2] should be a unique function of (H/T), for a given alloy so long as the impurities are in the Curie regime. Experimental values of the MR at several temperatures for the [Fe.sub.0.33][Zr.sub.0.67] alloy lie on a single curve of [Delta][Rho](H, T)/[[Rho].sup.2] vs. H/T

Magnetic tunnel junction (MTJ) structures were investigated by x-ray photoelectron spectroscopy. The Al layer was overoxidized and the samples were treated by rapid thermal annealing. It was found that the Mn atoms in the exchange-bias layer diffused into the magnetic layer, but did not reach the oxide barrier. Although slightly higher oxygen concentration was observed at the interface between the magnetic layer and the oxide barrier, strong evidence of the oxidized magnetic-layer interface was not found. Our result is consistent with the high tunneling magnetoresistance of MTJs at room temperature. [ABSTRACT FROM AUTHOR]

The Cr and Fe-doped bulk Ge-single crystal was fabricated using the vertical gradient solidification method and its magnetic properties were investigated using the superconducting quantum interference device (quantum device). The measured magnetic moment per Cr was 0.83 mu(sub B) at 5 K and it was probable that magnetically doped Ge and Si and related materials could open way to spintronic devices.

The temperature dependence of tunneling magnetoresistance (TMR) is studied for spin valve type double-barrier tunnel junctions. Normalized TMR values for double-barrier tunnel junctions (DBTJs) and single-barrier junctions (SBTJs) are plotted as functions of temperature and it is found that the DBTJ shows stronger temperature dependence of TMR than the SBTJ. The strong temperature dependence of TMR for the DBTJ is explained in terms of temperature dependence of the spin polarization of the middle magnetic layer and decrease of the spin coherence length with increasing temperature. [ABSTRACT FROM AUTHOR]

Magnetic tunnel junctions (MTJ) were fabricated with high oxygen-plasma power and the effects of annealing on the temperature dependence of tunneling magnetoresistance (TMR) were investigated experimentally. As grown, TMR increases, peaks around 160 K, and decreases with increasing temperature from 80 K to 300 K. When MTJs are annealed, T[sub max], the temperature at which maximum TMR is obtained, decreases as annealing temperature increases to the optimal point. In order to explain the temperature dependence of TMR, the difference of conductance between parallel and antiparallel alignments of magnetizations as a function of temperature is also analyzed. The shifts of T[sub max] due to annealing are described phenomenologically with spin-dependent transfer rates of electrons through the barrier. [ABSTRACT FROM AUTHOR]