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Researchers realize spin field effect transistors at room temperature

Graphene sketch-WSe2 spin field effect transistor. If the backgate voltage (Vbg) is zero, the spins are inversely signed as they propagate through the channel. In contrast, if Vbg is non-zero, precession is reduced and spin does not reverse the sign. Credit: Ingla-Aynes et al.

An important goal of spintronics research is to coherently manipulate electron spins at room temperature using electric current. This is of particular value as it allows the development of numerous devices, including spin field effect transistors.


In the experiment using Conventional materialSo far, engineers and physicists have only observed ballistic regimes and coherent spin precession at very low temperatures. However, 2D (2D material) has its own characteristics that can provide new control knobs for manipulating the spin matrix.

Researchers at CIC nano GUNE BRTA in Spain and the University of Regensburg in Germany recently room temperature When there is no magnetic field in the bilayer membrane Graphene.. In their treatise Physical review letter, They used 2D materials to realize spin field effect transistors.

“Our group has a long tradition of studying Spin transport “For example, with multiple materials, such as simple metals,” researchers conducting the study, Josep Ingla-Aynes, Franz Herling, Jaroslav Fabian, Luis E. Hueso, and Felix Casanova, emailed Phys.org. .. The goal is to understand how electron spins can carry information, and how this degree of freedom can help create devices with new capabilities. “

Graphene is one of the materials with the longest spin relaxation length. Nevertheless, manipulating spins moving over graphene can be very difficult and has so far been achieved only using an external magnetic field, which is not ideal for real-world applications. Hmm.

Recently, Ingla-Aynés and his colleagues have been investigating how heterostructures based on various 2D materials, also known as van der Waals heterostructures, work in spintronics. Van der Waals heterostructures are a class of graphene-based 2D materials with unbonded layers.

“We have specifically investigated the structure of a stack of materials with weak spin-orbit interaction (such as graphene) and materials with strong spin-orbit interaction (such as WSe).2Then, experimentally observing how this spin-orbit interaction is actually transmitted to graphene by proximity, “more technically, by achieving a strong interaction between layers, such Graphene (acting as an effective magnetic field) that can reverse spins without applying a magnetic field for efficient spin-orbit interaction. This is what we wanted to do. “

Instead of using a single material, Ingla-Aynés and his colleagues used a combination of two materials with different important properties. The first of these materials is graphene, which has weak spin-orbit interactions and long spin relaxation lengths. The second is WSe2, Strongly anisotropic Spin-orbit interaction..

“We prepared Double layer graphene/ WSe2 “Van der Waals heterostructures using dry polymer-based stacking techniques,” the researchers said. “Then, samples were annealed above 400 degrees Celsius to promote inter-layer proximity. To measure, we used a ferromagnetic electrode that can measure in-plane and out-of-plane spins moving across graphene / WSe in combination with a magnetic field.2 channel. “

Ingla-Aynés and his colleagues were able to control the spin transport time of the materials used by applying in-plane electric fields and backgate voltages. This ultimately enabled electrical control of spin precession at room temperature without the need for an external magnetic field.

“This has been sought after by the community for decades and has investigated many different materials, but so far no one has succeeded,” the researchers said. “Our device behaves like the long-awaited Datta-Das spin transistor, one of the goals of spintronics since it was first proposed in 1990, so this discovery impacts spintronics applicability. increase.”

In their treatise, researchers used the spin precession strategy they developed to present the first spin field-effect transistors at room temperature. In the future, their research may pave the way for practical implementations of energy-efficient spin-based logic.

“Our research also provides fundamental results as it provides valuable information on how spin transport is affected. Spin-orbit interaction Interactions in graphene-based van der Waals heterostructures, “the researchers said. “In the next study, we plan to study several other combinations of 2D materials that provide new physical effects related to spin degrees of freedom.”


Scientists Create Fully Electronic 2D Spin Transistors


For more information:
Electrical control of spin-precession evoked by Valley-Zeeman spin-orbit interaction at room temperature. Physical review letter(2021). DOI: 10.1103 / PhysRevLett.127.047202

© 2021 Science X Network

Quote: The researcher found the room temperature obtained from https://phys.org/news/2021-09-field-effect-transistor-room-temperature.html on September 7, 2021 (September 7, 2021). I noticed the spin field effect transistor.

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Researchers realize spin field effect transistors at room temperature

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