New Mechanism of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="italic">f</mml:mi></mml:math>-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="italic">f</mml:mi></mml:math>Exchange Interactions Controlled by Fermi Level Position

Story, T.; Górska, M.; Łusakowski, A.; Arciszewska, Μ.; Dobrowolski, W.; Grodzicka, E.; Golacki, Z.; Galazka, R. R.

doi:10.1103/physrevlett.77.3447

Cited by 53 publications

(38 citation statements)

References 14 publications

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“…Both the 5d and 4f orbitals can take part in a new coupling mechanism proceeding via intra-ion 4f-5d exchange interaction followed by inter-ion 5d-5d coupling mediated by charge carriers. 5,6 Teraguchi 7 et al have recently observed ferromagnetism in ternary alloy Ga 0.94 Gd 0.06 N films with a Curie temperature of 400 K. Moreover, even at this high concentration, Gd was shown to occupy predominantly Ga sites in the hexagonal GaN lattice.…”

Section: Introductionmentioning

confidence: 99%

Gd-doped GaN: A very dilute ferromagnetic semiconductor with a Curie temperature above 300 K

et al. 2005

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We present a systematic study of growth, structural, and magnetic characterization of GaN: Gd layers grown directly on 6H-SiC͑0001͒ substrates by reactive molecular-beam epitaxy with a Gd concentration ranging from 7 ϫ 10 15 to 2 ϫ 10 19 cm −3 . The structural properties of these layers are found to be identical to those of undoped GaN layers. However, the magnetic characterization reveals an unprecedented effect. The average value of the magnetic moment per Gd atom is found to be as high as 4000 B as compared to its atomic moment of 8 B . Such a colossal magnetic moment can be explained in terms of a long range spin polarization of the GaN matrix by the Gd atoms which is reflected by the circular polarization of magnetophotoluminescence measurements. Moreover, the material system is found to exhibit ferromagnetism well above room temperature in the entire concentration range under investigation. We propose a phenomenological model to understand the macroscopic behavior of the system. Our study reveals a close connection between the observed ferromagnetism and the colossal magnetic moment of Gd.

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Section: Introductionmentioning

confidence: 99%

Gd-doped GaN: A very dilute ferromagnetic semiconductor with a Curie temperature above 300 K

et al. 2005

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“…al. 12 in the theory explaining the Fermi energy dependence of the Gd-Gd exchange constant in SnGdTe mixed crystals. The 4f -5d interaction was also invoked by Dietl et.…”

Section: Introductionmentioning

confidence: 99%

Ground state splitting ofS8rare earth ions in semiconductors

Łusakowski

2005

Phys. Rev. B

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We propose a new mechanism leading to the ground state splitting for the rare earth 8 S ions in semiconductor crystals. The resulting splitting is due to three effects, the first is the intra atomic 4f − 5d spin-spin interaction, the second one is the spin -orbit interaction for 5d electrons and the third one is their hybridization with the valence band states of semiconductors host. The resulting splitting significantly depends on the relative position of 5d level with respect to semiconductor host band structure. We also discuss different model, already known in the literature, which is also based on ion -band states hybridization. For both models, as an example, we present results of numerical calculations for rare earth ion in IV-VI semiconductor PbTe.

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“…Unusual features of the exchange coupling between local magnetic moments at Gd3+ ions in Sn 1-x Gdx Te, and the recent discussion about a new mechanism of f-f exchange interactions in this semimagnetic semiconductor [1] attracted a new attention also to the host material, i.e. SnTe.…”

Section: Introductionmentioning

confidence: 99%

“…Story et al [1] noticed that the distance of the Fermi energy from the valence-band top defines a reasonable energy scale within which the arrangement of relevant energy levels can decide about the physical behaviour of the material. For S n 1 -x G d x T e , i t i s a s s u m e d t h a t t h e e x c h a n g e c o u p l i n g b e t w e e n l o c a l m o m e n t s a t Gd3+ ions (formed by f-states) is mediated by the unoccupied d-states which can hybridize with the band states.…”

Section: Introductionmentioning

confidence: 99%

Changes of Electronic Structure of SnTe Due to High Concentration of Sn Vacancies

Mašek¹,

Nuzhnyj²

1997

Acta Phys. Pol. A

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Non-stoichiometric Sn1-yΤe is a strongly degenerated n-type semiconductor. This is important for understanding unusual features of magnetic behaviour of Sn1-xGdxΤe where the relative positions of the Fermi energy and the atomic d-level of Gd govern the exchange coupling. The influence of the Sn vacancies on the band structure cannot be neglected if their concentration reaches a few atomic percent. We address this problem by using a tight-binding coherent potential approach and show that although the character of the bands remains unchanged, they are modified so that εd can come out above the heavy-hole band.

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New Mechanism off-fExchange Interactions Controlled by Fermi Level Position

Cited by 53 publications

References 14 publications

Gd-doped GaN: A very dilute ferromagnetic semiconductor with a Curie temperature above 300 K

Gd-doped GaN: A very dilute ferromagnetic semiconductor with a Curie temperature above 300 K

Ground state splitting ofS8rare earth ions in semiconductors

Changes of Electronic Structure of SnTe Due to High Concentration of Sn Vacancies

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