Magnetic fluctuations in 2D metals close to the Stoner instability

We consider the effect of potential disorder on magnetic properties of a two-dimensional metallic system (with conductance $g\gg 1$) when interaction in the triplet channel is so strong that the system is close to the threshold of the Stoner instability. We show, that under these conditions there is an exponentially small probability for the system to form local spin droplets which are local regions with non zero spin density. Using a non-local version of the optimal fluctuation method we find analytically the probability distribution and the typical spin of a local spin droplet (LSD). In particular, we show that both the probability to form a LSD and its typical spin are independent of the size of the droplet (within the exponential accuracy). The LSDs manifest themselves in temperature dependence of observable quantities. We show, that below certain cross-over temperature the paramagnetic susceptibility acquires the Curie-like temperature dependence, while the dephasing time (extracted from magneto-resistance measurements) saturates.Comment: 15 pages, 4 figure

A Case for Societal Digital Security Culture

Abstract. Information and communication technology systems, such as remote health care monitoring and smart mobility applications, have become indispensable parts of our lives. Security vulnerabilities in these systems could cause financial losses, privacy/safety compromises, and operational interruptions. This paper demonstrates through examples, that technical security solutions for these information systems, alone, are not sufficient to protect individuals and their assets from attacks. It proposes to complement (usable) technical solutions with Societal Digital Security Culture (SDSC): collective knowledge, common practices, and intuitive common behavior about digital security that the members of a society share. The paper also suggests a set of approaches for improving SDSC in a society and demonstrates using a case study how the suggested approaches could be integrated to compose a plan for improving SDSC