麻豆淫院

(麻豆淫院Org.com) -- In the early 20^th century, two famous discoveries about spin were made. One of them, discovered by Albert Einstein and Wander Johannes de Haas, explains a relationship between the spin of elementary particles. They found a relationship between magnetism and angular momentum. (Around that time, Einstein also put forth his theory of general relativity.) A little more than a decade later, Paul Dirac unveiled his equation dealing with a relativistic quantum mechanical wave, providing an explanation of electrons as elementary spin-1/2 particles.

Even though both of these discoveries have existed for nearly century, Sadamichi Maekawa tells 麻豆淫院Org.com, no one thought about combining them. 鈥淔or nearly 100 years, people did not study putting these together. We decided to combine different ideas to come up with a fundamental Hamiltonian to investigate mechanical rotations in the Dirac equation.鈥�

Maekawa, a scientist working with the Japan Atomic Energy Agency, as well as the Japan Science and Technology Agency, worked with scientists associated with Kyoto University and Tohoku University, to come up with a new model of spin that could be helpful in the development of spintronics. Mamoru Matsuo, Jun鈥檌chi Ieda and Eiji Saitoh were all involved in creating the new model, which is published in 麻豆淫院ical Review Letters: 鈥淓ffects of Mechanical Rotation on Spin Currents.鈥�

鈥淭he Einstein-de Haas effect is brought about by the angular momentum conservation between magnetism and rotational motion,鈥� Maekawa explains. 鈥淨uantum mechanics tells us that the origin of magnetism is electron spin. Recent progress in nanotechnology enables us to manipulate the flow of electron spins, or 鈥榮pin current鈥欌��. He points out that the relationship between spin current and magnets has been studied for nanodevice applications, but there has been little attention paid to the way rotational motion can be used to control spin current.

In Japan, Maekawa and his colleagues decided that studying how to use mechanical rotation to direct spin current could be advantageous in the development of spintronic devices that scientists think could eventually replace silicon-based electronics. 鈥淲e found that we needed to add general relativity to the equation,鈥� Maekawa says. 鈥淒irac included special relativity, but general relativity was needed as well. We combined the two Einstein theories, and added them to the theory of quantum mechanics. This way, we added mechanical rotation to the quantum equation.鈥�

Part of this new model includes extending the physical system into a noninertial frame from its present inertial frame. Maekawa and his fellows relied on the fact that the dynamics of spin currents is closely related to the spin-orbit interaction, resulting from using the low energy limit of the Dirac equation. 鈥淲e tried to combine general relativity and spin current, even though general relativity is not so popular in condensed matter physics right now,鈥� he explains. The result, Maekawa points out, is that it should be possible to control spin current using mechanical means.

For now, the model is theory. 鈥淲e formulated an equation, and in the future we hope to try the theory,鈥� Maekawa says. He believes that, 鈥渢his theory will give birth to nanoscale motor and dynamo,鈥� providing a practical way to realize spintronics in the future.

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