Negative correlation between the linear and the nonlinear conductance in magnetic tunnel junctions

The current-voltage (IV) characteristics beyond the linear response regime of magnetic tunnel junction (MTJ) is systematically investigated. We find a clear negative correlation between the two coefficients to characterize the linear (I alpha V) and the lowest-order nonlinear (I alpha V-3) currents, which holds regardless of the temperature and the thickness of the tunnel barrier. This observation cannot simply be explained by the standard tunneling model such as the Brinkman model, suggesting a mechanism intrinsic to MTJ. We propose a phenomenological model based on the Jullire model that attributes the observed negative correlation to the spin-flip tunneling assisted by a magnon. These results suggest a fundamental law between the linear and the nonlinear response of MTJ.

Automated summary

The study reveals a clear negative correlation between the linear and lowest-order nonlinear currents in the current-voltage characteristics of magnetic tunnel junctions (MTJ), which is independent of temperature and tunnel barrier thickness. A proposed phenomenological model based on the Julliere model attributes this negative correlation to spin-flip tunneling assisted by a magnon, suggesting a fundamental law governing the linear and nonlinear responses of MTJ.