Memristive Effects in Ionic Nanopores

Abstract

In the past 15 years much attention has been given to memristors, a type of passive electric circuit element that combine resistance with memory, characterised by a pinched hysteresis loop in the current-voltage diagram, when a periodic voltage is applied over the memristor. Ionic nanopores that connect aqueous electrolytes exhibit memristive behaviour and can be used as an actual realisation of a volatile memristor. In this thesis a general model for the conductivity and the hysteresis behaviour of memristors is developed from first principles. This model is applied to ionic nanopores, with consideration of the effect of changing the pore geometry and the frequency of the applied periodic voltage. To test the accuracy of the model, it is compared to finite-element calculations on cone-shaped and hourglass-shaped ionic nanopores. The analytic model is successful in predicting the number of crossings present in the hysteresis loops of pores with varying geometry, produced via finite-element calculations, and it revealed the role capacitive elements play in maintaining zero-crossing behaviour in memristors. We strongly encourage further experimental research into the memristive behaviour of nanopores.