Electronic transitions in GdN band structure

Journal Article · Wed May 28 00:00:00 EDT 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4880398· OSTI ID:22304278

Kita, T. ^[1]; Sakurai, T. ^[2]; Ohta, H. ^[3]

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1. Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Kobe 657-8501 (Japan)
2. Centre for Support to Research and Education Activities, Kobe University, 1-1 Rokkodai, Kobe 657-8501 (Japan)
3. Molecular Photoscience Research Center and Graduate School of Science, Kobe University, 1-1 Rokkodai, Kobe 657-8501 (Japan)

Using the near-infrared (NIR) absorbance spectroscopy, electronic transitions and spin polarization of the GdN epitaxial film have been investigated; and the GdN epitaxial film was grown by a reactive rf sputtering technique. The GdN film exhibited three broad bands in the NIR frequency regimes; and those bands are attributable primarily to the minority and majority spin transitions at the X-point and an indirect transition along the Γ-X symmetric direction of GdN Brillouin zone. We experimentally observe a pronounced red-shift of the indirect band gap when cooling down below the Curie temperature which is ascribed to the orbital-dependent coulomb interactions of Gd-5dxy electrons, which tend to push-up the N-2p bands. On the other hand, we have evaluated the spin polarization of 0.17 (±0.005), which indicates that the GdN epitaxial film has almost 100% spin-polarized carriers. Furthermore, the experimental result of GdN electronic transitions are consistent with the previous reports and are thus well-reproduced. The Arrott plots evidenced that the Curie temperature of GdN film is 36 K and the large spin moment is explained by the nitrogen vacancies and the intra-atomic exchange interaction.

• OSTI ID: 22304278
• Journal Information: Journal of Applied Physics, Vol. 115, Issue 20; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABSORPTION SPECTROSCOPY
BRILLOUIN ZONES
CARRIERS
COOLING
CURIE POINT
ELECTRONS
EPITAXY
EXCHANGE INTERACTIONS
FILMS
GADOLINIUM NITRIDES
NEAR INFRARED RADIATION
NITROGEN
RED SHIFT
SPECTROSCOPY
SPIN
SPIN ORIENTATION
SPUTTERING
SYMMETRY
VACANCIES