New platform for building nano-electronics and quantum processors

Measurement setup and type-z SOT switching. (a) Crossbar geometry with Ix, Iy , σsw, and σbi inside. (b) Nonvolatile measurement sequence. Write and read processes are separated in the time domain. (c) Anomalous Hall resistance Rxy as a function of Hz . The maximum _Rxy = 210 m_. (d) SOTinduced magnetization switching with a bias field Hx of 500 Oe. Opposite Hx leads to opposite switching chirality. Credit: FEFU press office

Scientists of Far Eastern Federal University (FEFU, Vladivostok, Russia) together with colleagues from the Chinese Academy of Sciences (Beijing) have designed a platinum-cobalt-magnesium oxide microstructure coated by platinum that is capable of operating in three-valued logic mode (true/false/don’t know).

The team has developed a cross-shaped microstructure consisting of nanometer layers of platinum, cobalt (just 0.8 nm), magnesium oxide, and a coating layer of platinum. The structure can be a single platform performing simultaneously as a processor and a memory chip.

To obtain the spin current and affect the cobalt layer, the scientists applied two cross-currents and an in-plane magnetic field to shift magnetic symmetry. At the same time, they induced a short-impulse current passing through the lower layer of platinum. As a result, the spins of electrons with different polarity (oriented “up” and “down,” corresponding to the modes 1 and 0) turned to opposite surfaces of the platinum layer, producing a pure spin current that affected the spins of the electrons of the magnetic layer. Under certain conditions, spins of the cobalt layer were switched. It meant the cell switched from 0 to 1 in analogy.

Due to current pulses, which were passed through two other orthogonally (perpendicularly) located contacts, it was possible to control different magnetic states in the cobalt layer, thus implementing different states of the three-valued logic. Logical operations as AND, OR, NOT-AND and NOT-OR can be called in the structure by the means of a certain sequence of cross-currents.

It paves the way for building new electronic and spintronic devices, qutrit quantum processors (three positions instead of two of qubits).

A related article is published in Physical Review Applied.