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Half-Metallic Bandgap Measurement Using Circularly Polarized Infrared Light

Department of Electronic Engineering, University of York, York YO10 5DD, UK

Present address: National Center for Nanotechnology and Semiconductors, King Abdulaziz City for Science and Technology (KACST), Riyadh 11442, Saudi Arabia.

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Takahide Kubota

Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan

Center for Spintronics Research Network, Tohoku University, Sendai 980-8577, Japan

Present address: Advanced Spintronics Medical Engineering (ASPIME), Graduate School of Engineering, Tohoku University, Sendai 980-0845, Japan.

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Jun-Young Kim

Department of Physics, University of York, York YO10 5DD, UK

Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research, Singapore 138632, Singapore

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Koki Takanashi

Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan

Center for Spintronics Research Network, Tohoku University, Sendai 980-8577, Japan

Center for Science and Innovation in Spintronics Core Research Cluster, Tohoku University, Sendai 980-8577, Japan

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, and

Atsufumi Hirohata

https://orcid.org/0000-0001-9107-2330

Department of Electronic Engineering, University of York, York YO10 5DD, UK

E-mail Address: [email protected]

Corresponding author.

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https://doi.org/10.1142/S2010324723500078Cited by:0 (Source: Crossref)

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Abstract

One avenue toward next-generation spintronic devices is to develop half-metallic ferromagnets with 100% spin polarization and Curie temperature above room temperature. Half-metallic ferromagnets have unique density of states, where the majority spins are metallic but the minority spins are semiconducting with the Fermi level lying within an energy gap. To date, the half-metallic bandgap has been predominantly estimated using Jullière’s formula in a magnetic tunnel junction or measured by the Andreev reflection at low temperature, both of which are very sensitive to the surface/interface spin polarization. Alternative optical methods such as photoemission have also been employed but with a complicated and expensive setup. In this study, we developed and optimized a new technique to directly measure the half-metallic bandgap by introducing circularly polarized infrared light to excite minority spins. The absorption of the light represents the bandgap under a magnetic field to saturate the magnetization of a sample. This technique can be used to provide simple evaluation of a half-metallic film.

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