Bio-inspired heat-based logic in CuMnAs antiferromagnetic analog memory device (IMAGE)
Caption
Illustration of the similarity between a CuMnAs-based antiferromagnetic analog memory device and a biological synapse.
a, In a biological synapse, the presynaptic and postsynaptic neurons are separated by a 20 to 40 nm thick gap, called a synaptic cleft. When presynaptic neurons are activated, they release neurotransmitters into the synaptic cleft, which then bind to receptors in a postsynaptic neuron and cause it to become active. Since the release of neurotransmitters is initiated by the intracellular calcium concentration (Ca2+), the complex kinetics of Ca2+ leads to a transient change in the synaptic weight, working as a short-term memory (STM). b, The increase of a number of postsynaptic receptors (shown in green) on longer time scales leads to long-term memory (LTM). c and d, Schematic representation of a CuMnAs-based memory device in which the ultrafast change in reflectivity and heat dissipation from the CuMnAs layer (red arrows) after excitation by a single femtosecond laser pulse (red column) play the role of STM and the device resistance increase due to magnetic switching plays the role of LTM. e, Multistore psychological model of human memory, which illustrates that information from a "sensor" is transferred from (STM) to (LTM) only after frequent rehearsal. f, In the device, laser pulse bursts are used as input stimuli and absorption in CuMnAs serves as the sensor. Note that pulse widths of 150 fs are strongly exaggerated with respect to their time spacing of 700 ps for clarity in f (see the inset). g, Schematic depiction of a transient increase of effective CuMnAs temperature after absorption of the shown number of laser pulses; at room temperature (RT) the required temperature threshold (TTH) for achieving the switching is overpassed only for 8 and 16 pulses. h, Measured resistivity increase DR in a device made from a 20‑nm‑thick CuMnAs epilayer, which shows that the number of rehearsals for information to be transferred from STM do LTM has to be at least 8 within the used 10‑ns‑long memorizing period.
Credit
Prof. Petr Nemec, petr.nemec@matfyz.cuni.cz
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License
CC BY