| Posted: Mar 02, 2016 | |
Spinning better electronic devices(Nanowerk News) A team of researchers, led by a group at the University of California, Riverside, have demonstrated for the first time the transmission of electrical signals through insulators in a sandwich-like structure, a development that could help create more energy efficient electronic devices. |
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 Jing Shi, a professor of physics. Conventional electronic devices rely on the transport of electrons in a semiconductor such as silicon. Now, researchers are exploiting the 'spin' of the electron rather than its charge to create a new generation of 'spintronic' devices that are potentially more energy efficient and more versatile than those currently making up silicon chips and circuit elements. The UC Riverside-led research, which was published online Wednesday (March 2) in the journal Nature Communications ("Observation of magnon-mediated current drag in Pt/yttrium iron garnet/Pt(Ta)trilayers"), is significant because it demonstrates that a tri-layer, sandwich-like, structure can serves as a scalable pure spin current device, an essential ingredient in spintronics. A key element in this breakthrough is the material. To demonstrate the effect, the magnetic insulator needs to be truly insulating, or there will be a parasitic signal from leakage. On the other hand, a high-quality magnetic insulator grown on metal had never been demonstrated. |
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| Using combination of sputtering (for metals) and pulsed laser deposition (for insulator), we successfully showed that the 50-100 nanometer thick magnetic insulator, such as yttrium iron garnet, is not only magnetic and insulating, but also of high quality when it is grown on 5 nanometer thick platinum. | |
| In the structures used by the researchers, there are two metals and a magnetic insulator in between. The metals are for spin current generation and detection (conversion of spin current back to charge current) via the so-called spin Hall effect and inverse spin Hall effect. | |
| The magnetic insulator is an electrical insulator but a good spin current conductor. The spin current flowing in the insulator does not involve mobile electrons therefore it does not dissipate energy as an electrical current does in joule heating. | |
| The researchers have also demonstrated that the signal transmission can be switched on and off and modulated in its strength by a magnetic field. The electrical signal transmission through the magnetic insulators can be switched on and off depending on the magnetic state, or direction of the magnetization, of the magnetic insulators. | |
| So the direction of the magnetization can be regarded as a memory state of non-volatile random access memory devices. In addition, the signal level can be modulated by changing the direction of the magnetization; therefore, it can also be used as analog devices. The sandwich structure can be made small by nanofabrication so that the devices can be scaled down. |
| Source: University of California - Riverside | |
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