High current density self-field effects and low-frequency noise in NiFe/Ag GMR multilayers

Abstract

High current densities ( 106-107 A/cm2) produce magnetic fields which can induce antiparallel magnetic alignment in large (16 pm and 8 pm) NiFe/Ag thin film multilayer devices. We induce GMR in unannealed devices which normally do not display GMR. We find multiple peaks in the magnetoresistance curves of annealed and unannealed devices. Analysis of the positions and shapes of these magnetoresistance peaks provides a new set of tools for determining the micromagnetic structure of the multilayers. Our magneto-opticaI Kerr effect data and low frequency noise data correlate with the magnetoresistance peaks and may yield further information about layer-layer interactions and domain structure.

Low-Frequency Magnetic Noise in Micron-Scale Magnetic Tunnel Junctions

“…Also, the total transition rate of the effective two-level system responsible for the Lorentzian noise within the peak was found to be completely independent of applied bias [8]. Consequently, neither spin-dependent traps nor currentinduced magnetic fields can be responsible for the noise [9,10]. Owing to surface tension, moreover, the vibrational excitations of domain walls result in high-frequency noise.…”

Observation of a fluctuation-enhanced magnetoresistance inNi81Fe19/AgRogers1, Kirschenbaum2, Beale3 et al. 1997Phys. Rev. B2000View full textAdd to dashboardCite

“…One of the most striking effects we have previously reported 13,14 is the observation of multiple peaks in the MR curves for devices under high dc current density bias. Figure 1 shows examples of multipeaked MR curves for 5-, 7-, and 9-layer devices near 10 7 A/cm 2 dc bias.…”