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| Free Column – page 4 |
Memristance: influence of dislocations and local heating during operationby Andrey Shkabko, MaNEP/Solid State Chemistry and Catalysis at EMPA, Duebendorf |
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A memristor is the 4th circuit element apart from resistor, capacitor and inductor, which
exhibits stable resistivity switching. Typically, a memristor consists of a ceramic material
sandwiched between two metals served as contacts, and, as a great opportunity for potential
application, it is possible to downscale the size of the memristor to nanoscale. However, not only
scalability but also new transport phenomena have attracted the attention of researchers all over the world since last 40 years, when the theoretical basis of the time-varying function of the net charge flown through the system was introduced1.
Several ceramics with metallic contacts showed memristive effect and every system has a range of features assigned to explain it. Theoretically predicted memristors have an important property linked with the nanostructure of the ceramic matter and, as it was showed recently, coupled ion-electron conductivity is responsible for the memristance 2,3. |
An application of high enough voltages allow to move not only
electrons/holes but also ions/vacancies.Prior observation
of resistivity switching the process similar to electropoling in case of piezoelectric materials and
magnetization in case of ferromagnetic materials has to be applied. During this process ceramic
matter of the memristor generally needs to be electroformed by applying a positive voltage
threshold, when oxygen ions are attracted by the anode interface and all transport phenomena
occurs at the metal/ceramic interface. In our work we developed materials by changing the anionic sublattice of perovskite-type titanates which has the feature generally applied for nearly all memristive systems. This feature is controlled fabrication of characteristic dislocations in perovskite structure allowing decrease the time of electroformation and facilitates switching. As a passive element, the memristor during the operation dissipate Joule heat and by increase of electron current promote thermal redox processes at the anode interface 4.
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The obtained results will help to understand further steps in the materials design of the
memrisistive system and the improvements of the metal/ceramic interfaces to force the realization of new types of devices for future biological and semiconducting applications.
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