UNN researchers obtain nanostructures with spin memory effect
Researchers at UNN's Physics and Technology Research Institute (PTRI) have succeeded in growing semiconductor nanostructures with a spin memory effect, a high-density and non-volatile magnetic memory based on quantum technologies. Physicists and technologists created the structure consisting of an ultra-thin layer of magnetic manganese (Mn) atoms, which is located a few nanometers away from the gallium arsenide (GaAs) semiconductor quantum well, and demonstrated recording and reading information using polarized light pulses.
Today, such hybrid platforms combining the properties of a semiconductor diode and a magnetic memory element are being developed by many research teams in Russia and around the world, primarily in the United States and Japan. The characteristics of the structure created at the UNN PTRI are on par with those of the best samples. Nizhny Novgorod scientists managed to achieve a stable spin memory effect in a nanostructure with atomically thin layers of magnetic atoms. The effect was recorded by a team of scientists led by Dr. Mikhail Dorokhin. The results of this research were published in the leading international journal Physical Review B.
Spin memory is one of the main focus areas in spin electronics. It involves quantum technology that is based on controlling the magnetic moments of electrons. Each electron carries not only a charge, but also a spin, its own magnetic moment, which creates a magnetic field around itself. This can be controlled when the electron is "trapped" in a quantum well, an ultrafine semiconductor layer that limits the motion of the particle. The electron spin can be rotated and oriented in different directions, like a compass arrow. By means of these switches, information is encoded in the spin memory. By "recording" and "reading" magnetic moments of electrons and atoms, it is possible to create faster and more energy efficient components for modern electronics. Thus, traditional semiconductor diodes, LEDs and transistors will be replaced with their spin analogues. This requires a material that has the properties of both a semiconductor and a permanent magnet.
Obtaining hybrid structures that contain semiconductor and magnetic layers is one of the main lines of work for an international team of scientists from Lobachevsky University’s PTRI and Faculty of Physics, the University of Campinas, and the University of Uberlandia (Brazil). These research centres have been working on projects in the field of spin electronics for more than 15 years. Brazilian colleagues help Nizhny Novgorod researchers to manipulate the magnetic properties of samples, exposing the samples to ultrafast femtosecond laser pulses. It is with the help of this technique that the spin memory effect was discovered in the latest study. An optical pulse creates polarization, i.e. a difference in the number of magnetic moments of different orientations, in a quantum well with a layer of gallium arsenide (GaAs) in its centre. The electrons polarize and magnetize the neighbouring nanolayer of manganese (Mn) atoms, which, in turn, remembers and preserves this polarization.
This technology base can become one of the components of Russian nanoelectronics and spintronics. The team of scientists is planning to describe the physics of the microscopic processes in more detail and to determine the parameters with a higher accuracy.
