Search

Self-assembled structures are possible solutions to the problem of increasing the density and connectivity of memristive units in massive arrays. Although they would allow surpassing the limit imposed by the lithographic feature size, the spontaneous formation of highly interconnected networks poses a new challenge: how to characterize and control the obtained assemblies. In view of a flourishing field of such experimental realizations, this study explores the collective electrical response of simulated memristive units when assembled in geometrically organized and progressively distorted configurations. We show that highly idealized memristive arrays already display a degree of complexity that needs to be taken into account when characterizing self-assemblies to be technologically exploited. Moreover, the introduction of simple distortions has a considerable impact on the available resistance states and their evolution upon cycling. Considering arrays of a limited size, we also demonstrate that the collective response resembles aspects of the individual model while also revealing its own phenomenology.

10 MeV proton-irradiation effects on a YBCO-based test structure were analyzed by measuring its current-voltage (IV) characteristics for different cumulated fluences. For fluences of up to $\sim$80$\cdot$10$^9$~p/cm$^2$ no changes in the electrical behavior of the device were observed, while for a fluence of $\sim$~300$\cdot$10$^9~$ p/cm$^2$ it becomes less conducting. A detailed analysis of the room temperature IV characteristics based on the $\gamma$ power exponent parameter [$\gamma=dLn(I)/dLn(V)$] allowed us to reveal the main conduction mechanisms as well as to establish the equivalent circuit model of the device. The changes produced in the electrical behavior, in accordance with Monte Carlo TRIM simulations, suggest that the main effect induced by protons is the displacement of oxygen atoms within the YBCO lattice, particularly from oxygen-rich to oxygen-poor areas, where they become trapped., Comment: 22 pages, 7 figures, corresponding author: acha@df.uba.ar

In this work the first results obtained by LabOSat-01 platform are presented. This platform was designed for testing custom devices on board of small satellites. Two LabOSat-01 type boards were launched and placed into Low Earth Orbit (LEO) on May 30, 2016. We present here an analysis of data collected by one of these boards during the first days of mission. Total Ionization Dose results are compared with data acquired by LabOSat-01`s predecessor board, MeMOSat-01, launched in 2014.

An YBCO-based test structure corresponding to the family of ReRAM devices associated with the valence change mechanism is presented. We have characterized its electrical response previous to its lift-off to a Low Earth Orbit (LEO) using standard electronics and also with the dedicated LabOSat-01 controller. Similar results were obtained in both cases. After about 200 days at LEO on board a small satellite, electrical tests started on the memory device using the LabOSat-01 controller. We discuss the results of the first 150 tests, performed along a 433-day time interval in space. The memory device remained operational despite the hostile conditions that involved launching, lift-off vibrations, permanent thermal cycling and exposure to ionizing radiation, with doses 3 orders of magnitude greater than the usual ones on Earth. The device showed resistive switching and IV characteristics similar to those measured on Earth, although with changes that follow a smooth drift in time. A detailed study of the electrical transport mechanisms, based on previous models that indicate the existence of various conducting mechanisms through the metal-YBCO interface showed that the observed drift can be associated with a local temperature drift at the LabOSat controller, with no clear evidence that allows determining changes in the underlying microscopic factors. These results show the reliability of complex-oxide non-volatile ReRAM-based devices in order to operate under all the hostile conditions encountered in space-borne applications., Comment: 20 pages, 11 figures