SCIENTISTS HAVE CREATED A 'MAGNETIC SPIN ICE" FOR STORING INFORMATION
The distribution of positive (red) and negative (blue) charges on the surface of spin ice. Photo: Yong-Lei Wang and Zhili Xiao
Physicists from the US have proposed a new system for recording and storing information on the basis of the so-called "spin ice" structure with an ordered system of nuclear magnetic moments. Unlike previous systems, the new design allows easier and more accurate to record and store large amounts of information.
Spin ice structure in which the magnetic moments of the spins of the atoms are the same as the conventional protons in ice: two look to the outside, and two inside cell of the crystal. In each magnetic cell of the crystal ice in four half spins — magnetic charges. Different orienting the spins in the cells, the ice crystals can be recorded and then read from them. According to the authors of a new study, in the future this recording method is useful for powerful and compact computers and quantum computing. However, current systems are not accurate and need to be revised.
In an article in the journal Science, a team of scientists from the USA showed how to generate cells with a large number of degrees of freedom, working more precisely and more reliable. For this, the researchers suggested mentally break each magnetic spin structure on a two unit magnetic charge, and then to connect them together in another way- not as in a classical crystal artificial spin ice. When this happens, the system in which spins are oriented not only horizontally and vertically but also diagonally. The illustration shows how the will is located the magnetic spins.
Schematic representation of the magnetic moments in crystals of artificial spin ice. Photo: Yong-Lei Wang and Zhili Xiao
Thus, each new cell will acquire additional diagonal degree of freedom, increasing the available number of States by half. In total, each cell can be in one of eight States that the researchers divided into three groups, two, two and four state energy.
To overcome the energy barrier of the transition state at room temperature succeeded in imposing external magnetic fields on the system. In the work scientists have proposed an approach that allows you to flip individual spins in a given cell, thereby changing the scatter condition of the cells. This used magnetic force microscope, equipped with a two-dimensional vector magnet, and pilot a system of nanoislands (300х80х25 nm) of permalloy deposited on a substrate from a mixture of silicon and its oxide.
The figure shows an example of the use of a new approach to recording information on the background of the substrate mostly very nizkoenergeticke as the written word ICE (English "ice") cells of the excited state. The system is renewable, that is, the same substrate can be repeatedly "reset", and then overwrite.
Magnetic force image of the word ICE written on the magnetic artificial spin ice. Photo: Yong-Lei Wang and Zhili Xiao
The study authors noted that the developed approach is universal and can be used to create more complex structures with a large number of the States having, respectively, a large information capacity. The application of new technology — selected topics quantum electronics, as well as the encoding and storage of information. In addition, the system of artificial ice is suitable for recording and transferring the pattern of magnetization on other elements or the detailed study of the magnetic properties of defects such as magnetic monopole, or Dirac wave.