Electrical spin injection from spin gapless semiconductor into p-Si via SiO2 tunnel barrier

What is it about?

Dr. T. K. Nath and his group at IIT Kharagpur have developed thin films of a novel magnetic material, Mn₂CoSi (MCS), which belongs to the class of inverse Heusler alloys. These materials are of great interest for spintronic applications due to their unique ability to transport spin-polarized carriers without energy loss. The MCS films were grown on p-type silicon (Si) substrates using electron beam physical vapor deposition. Structural analyses using cross-sectional transmission electron microscopy (TEM) and scanning electron microscopy (SEM) confirmed the formation of a uniform, polycrystalline MCS/SiO₂/p-Si heterostructure. Magnetic measurements revealed that the films are ferromagnetically soft with an in-plane easy axis and a Curie temperature significantly higher than room temperature, making them suitable for device operation under ambient conditions. From a functional perspective, the device exhibited magnetic diode-like current–voltage behavior across a wide temperature range (78–300 K), with a temperature coefficient of resistance (TCR) of –2.09 × 10⁻⁹ Ω·m/K — a characteristic value for spin gapless semiconductors. In more accessible terms, Dr. Nath’s team demonstrated that the MCS film can effectively inject and detect electron spins — the tiny magnetic moments of electrons — into the silicon layer at room temperature using a three-terminal Hanle setup. They measured a spin lifetime of around 78 picoseconds and a spin diffusion length of 167 nanometers, both promising indicators for future spin-based electronic devices. These results indicate that this MCS-based heterostructure could be a key component in developing next-generation spintronic technologies that are faster, more energy-efficient, and compatible with existing semiconductor platforms.

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Photo by Jeswin Thomas on Unsplash

Photo by Jeswin Thomas on Unsplash

Why is it important?

Dr. Nath’s team demonstrated that the MCS film can effectively inject and detect electron spins — the tiny magnetic moments of electrons — into the silicon layer at room temperature using a three-terminal Hanle setup. They measured a spin lifetime of around 78 picoseconds and a spin diffusion length of 167 nanometers, both promising indicators for future spin-based electronic devices. These results indicate that this MCS-based heterostructure could be a key component in developing next-generation spintronic technologies that are faster, more energy-efficient, and compatible with existing semiconductor platforms.

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