In recent years, research on spintronics, a technology that uses the spin states of particles to store and process information, has been constantly advancing towards new frontiers. A new study by Chinese scientists reveals the possibility of realizing the coherent optical spin Hall effect (OSHE) at room temperature; This could fundamentally change the way we think about spintronic devices.

The scientific study was published in the journal Nature Supplies. Exciton polaritons are quantum objects (liquid light), which are the superposition of material quasiparticles, excitons (bound electrons and holes) and light quantum, photons, placed in special semiconductor microresonators. These unique particles have spin properties, making them ideal candidates for transmitting spin currents over long distances.

Since its inception in the early 21st century, spintronics has attracted the attention of scientists for its ability to potentially outperform traditional electronic technologies. However, due to the complex nature of spin interactions and fast spin relaxation, spin computing devices have proven difficult to implement. Previous studies have shown that energy divisions associated with crystal symmetry prevent the stable flow of pure spin current.

If the spin carriers are polaritons, the strong effective magnetic field of polariton microresonators must be taken into account when creating the devices, which rapidly rotates the spin of polaritons and makes the use of spin current difficult. However, the use of a superfluid polariton liquid formed in an organic–inorganic hybrid FAPbBr microcavity with an isotropic cubic crystal structure overcomes this problem, allowing highly coherent spin currents to be obtained. Spins in such a structure are transported by superfluid polariton flows, making it possible to solve the problem of rapid dissipation caused by thermal fluctuations, allowing the spintronic device to operate at room temperature.

The scientists also implemented two innovative spintronic devices: a logical NOT gate and a spin-polarized beam splitter. The logic gate can change the right circular polarization of the spin to left and vice versa, and the beam splitter splits the linearly polarized light into two beams with opposite spins. These devices can operate at ultrafast picosecond time scales, far ahead of today’s electrical devices that operate at nanosecond time scales. A nanosecond is a billionth of a second, and a picosecond is a thousand times smaller. This means that such spintronic devices can operate a thousand times faster than modern electronic devices.

Physicists have conducted both theoretical calculations and experimental research. Theoretical calculations consisted of solving the two-component controlled dissipative Schrödinger equation describing the motion of polaritons. The simulation involved calculating the spin components of the wave function and examining the effect of the random potential on the spin states. This contributed to a deeper understanding of the processes occurring in polariton flows and made it possible to predict how they could be used in spintronic devices.

The result of the simulation was the prediction that liquid light particles can propagate ballistically while maintaining a coherent state. The experiment showed that at room temperature polaritons can fly up to 60 micrometers without disturbing their state; This is more than sufficient for use as spin current carriers in spintronic devices. This was confirmed by observation of interference bands.

In addition, theoretical calculations predicted that the spin state of liquid light particles oscillates along the propagation path, which makes it possible to control it and reverse polarization using a magnetic field. The described effect has been demonstrated experimentally with the help of laser excitation of the supercurrent polariton flow. When a linearly polarized laser beam excited a microresonator, spin states of polaritons were formed depending on the direction of their angular moments. The observed effect makes it possible to effectively control the direction of spin currents and use them for calculations.

“All-optical logic circuits will be able to provide high data processing speed with low energy consumption, which is especially important in the era of big data and artificial intelligence. This will not only lead to an increase in the performance of modern computer systems, but also to the emergence of new innovative applications in the field of quantum computing, information processing and data transmission.” “This could lead to the creation of more compact, powerful and weather-resistant devices that could change the way we approach the design and architecture of future computer systems.”

This work is an important step forward in the field of spintronics and polaritonics. Scientists have opened new horizons for the practical application of excitonic polaritons at room temperature, and this could lead to revolutionary changes in the technologies we use every day.