Magnetic fluctuations in two-dimensional metals close to the Stoner instability

Abstract

We consider the effect of potential disorder on the magnetic properties of a two-dimensional metallic system (with conductance $g\ensuremath{\gg}1)$ when the 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 nonzero spin density. Using a nonlocal 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 LSD's manifest themselves in the temperature dependence of the observable quantities. We show that below a certain crossover temperature the paramagnetic susceptibility acquires a Curie-like temperature dependence, while the dephasing time (extracted from magnetoresistance measurements) saturates.

Locations

• Physical review. B, Condensed matter - View
• arXiv (Cornell University) - View - PDF
• DataCite API - View