Statistical properties of currents flowing through tunnel junctions

Abstract

*This paper presents an overview of the statistical properties arising from the broadness of the distribution of tunnel currents in metal-insulator-metal junctions. Experimental current inhomogeneities can be modelled by a lognormal distribution and the size dependence of the tunnel current is modified at small sizes by the effect of broad distributions.

In situ TEM studies of local transport and structure in nanoscale multilayer films

“…Even when characterization tools with high spatial resolution are used to identify the presence of such defects ex situ, it is difficult to isolate the contribution of each factor and then to correlate this with the observed magnetotransport behavior. For example, it has been shown by scanning probe spectroscopy techniques that the nanometer-scale site-specific tunneling currents measured at different positions on MTJ sheet films obey a lognormal distribution [10] and can vary by several orders of magnitude. This is a result of the exponential dependence of tunneling current on Gaussian distributed properties of the tunneling barrier such as the spatial width (in nm) and height (in volts) [11], with the large range of tunneling currents observed in point probe studies [12,13] resulting from relatively small fluctuations in the actual barrier width and height.…”

Asymmetry of the magnetization reversal process in a magnetic tunnel junction

“…This implies that for the local coupling field, a slight decrease in d with respect to its macroscopic value produces a much higher difference than the equivalent increase in d. Even in the case of a barrier that would exhibit a random distribution of thickness d over the sample, the coupling field would be expected to be asymmetric since, by definition, the exponential of a Gaussian random variable is a lognormal random variable. 25 In our case, starting already from a nonsymmetric d distribution ͓Fig. 1͑c͔͒, we all the more expect an asymmetrical local coupling field distribution as sketched in Fig.…”

Tunnel transport through CoFe2O4 barriers investigated by conducting atomic force microscopy

“…Further, this difference is independent of the voltage applied during Turning to a more quantitative description, we consider a Gaussian distribution (σ) of local barrier thicknesses. Then P(I) should be a log-normal distribution [8]:…”

“…(inset figure 3a). According to Refs [8],. the P(I) distribution can be better fitted using the log-log data representation (inset figure 3b).…”