Electrolyte gated synaptic transistor based on an ultra-thin film of La_0.7Sr_0.3MnO₃

Developing electronic devices able to reproduce efficiently synaptic functionality is essential towards implementing fast and low energy consuming neuromorphic computing systems. Hybrid ionic/electronic three-terminal synaptic transistors are promising as artificial synapses since they can process information and learn simultaneously. In this work, we report on an electrolyte gated synaptic transistor based on an ultra-thin epitaxial film of La_0.7Sr_0.3MnO₃ which is close to a metal-insulator transition. The dynamic control of oxygen composition of the manganite ultra-thin film with voltage pulses applied through the gate terminal allows reversibly modulating its electronic properties in a non-volatile manner. The conductance modulation can be finely tuned with the amplitude, duration and number of gating pulses, providing different alternatives to gradually update the synaptic weights. The transistor implements essential synaptic features such as excitatory postsynaptic potential, paired-pulse facilitation, long-term potentiation/depression of synaptic weights and spike-time-dependent plasticity (STDP). These results constitute an important step for the development of neuromorphic computing devices based on correlated manganites and open new paths towards enhancing the functionalities of synaptic transistors by using a half metallic ferromagnet as the transistor channel.