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Anisotropic Quantum Transport through a Single Spin Channel in the Magnetic Semiconductor EuTiO 3
Author(s) -
Maruhashi Kazuki,
Takahashi Kei S.,
Bahramy Mohammad Saeed,
Shimizu Sunao,
Kurihara Ryosuke,
Miyake Atsushi,
Tokunaga Masashi,
Tokura Yoshinori,
Kawasaki Masashi
Publication year - 2020
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201908315
Subject(s) - condensed matter physics , spintronics , materials science , semiconductor , electron mobility , magnetization , magnetic semiconductor , ferromagnetism , anisotropy , magnetic anisotropy , spin (aerodynamics) , electron , magnetic field , physics , optoelectronics , quantum mechanics , thermodynamics
Abstract Magnetic semiconductors are a vital component in the understanding of quantum transport phenomena. To explore such delicate, yet fundamentally important, effects, it is crucial to maintain a high carrier mobility in the presence of magnetic moments. In practice, however, magnetization often diminishes the carrier mobility. Here, it is shown that EuTiO 3 is a rare example of a magnetic semiconductor that can be desirably grown using the molecular beam epitaxy to possess a high carrier mobility exceeding 3000 cm 2 V −1 s −1 at 2 K, while intrinsically hosting a large magnetization value, 7 μ B per formula unit. This is demonstrated by measuring the Shubnikov–de Haas (SdH) oscillations in the ferromagnetic state of EuTiO 3 films with various carrier densities. Using first‐principles calculations, it is shown that the observed SdH oscillations originate genuinely from Ti 3 d ‐ t 2g states which are fully spin‐polarized due to their energetical proximity to the in‐gap Eu 4 f bands. Such an exchange coupling is further shown to have a profound effect on the effective mass and fermiology of the Ti 3 d ‐ t 2g electrons, manifested by a directional anisotropy in the SdH oscillations. These findings suggest that EuTiO 3 film is an ideal magnetic semiconductor, offering a fertile field to explore quantum phenomena suitable for spintronic applications.