Shift in the absorption edge due to exchange in teraction in ferromagnetic semiconductors

Natalia Lebedeva, Pekka Kuivalainen

Research output: Contribution to journalArticleScientificpeer-review

2 Citations (Scopus)

Abstract

We develop the theory of the shift in the band edge caused by a strong exchange interaction between charge carrier spins and the spins of the localized magnetic electrons in ferromagnetic semiconductors.
The one-particle Green function is derived by using Matsubara's temperature Green functions, and then an infinite-order correction to the band edge due to the exchange interaction is determined from the poles of the Green function. With the aid of the temperature- and magnetic field-dependent spin polarization of the magnetic moments and the spin correlation functions, the band edge can be calculated as a function of temperature in various magnetic fields.
The calculated results are compared to experimental data in the cases of the ferromagnetic semiconductors EuO and Ga1-xMnxAs over a wide temperature range. For these materials the values 0.223 and 1.4 eV are evaluated for the exchange interaction parameter, respectively.
A new feature is found in the ferromagnetic region, as a result of the exceptionally strong exchange interaction in Ga1-xMnxAs, i.e., a blue-shift in the band edge with decreasing temperature or with increasing
Original languageEnglish
Pages (from-to)4491-4501
JournalJournal of Physics: Condensed Matter
Volume14
Issue number17
DOIs
Publication statusPublished - 2002
MoE publication typeA1 Journal article-refereed

Fingerprint

Exchange interactions
Green's function
Semiconductor materials
Green's functions
shift
interactions
Magnetic fields
Temperature
Spin polarization
temperature
Magnetic moments
Charge carriers
blue shift
magnetic fields
charge carriers
Poles
Temperature distribution
temperature distribution
poles
magnetic moments

Keywords

  • magnetic semiconductors
  • ferromagnetic materials
  • band gap blue shift
  • band shift

Cite this

Lebedeva, Natalia ; Kuivalainen, Pekka. / Shift in the absorption edge due to exchange in teraction in ferromagnetic semiconductors. In: Journal of Physics: Condensed Matter. 2002 ; Vol. 14, No. 17. pp. 4491-4501.
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Shift in the absorption edge due to exchange in teraction in ferromagnetic semiconductors. / Lebedeva, Natalia; Kuivalainen, Pekka.

In: Journal of Physics: Condensed Matter, Vol. 14, No. 17, 2002, p. 4491-4501.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Shift in the absorption edge due to exchange in teraction in ferromagnetic semiconductors

AU - Lebedeva, Natalia

AU - Kuivalainen, Pekka

PY - 2002

Y1 - 2002

N2 - We develop the theory of the shift in the band edge caused by a strong exchange interaction between charge carrier spins and the spins of the localized magnetic electrons in ferromagnetic semiconductors. The one-particle Green function is derived by using Matsubara's temperature Green functions, and then an infinite-order correction to the band edge due to the exchange interaction is determined from the poles of the Green function. With the aid of the temperature- and magnetic field-dependent spin polarization of the magnetic moments and the spin correlation functions, the band edge can be calculated as a function of temperature in various magnetic fields. The calculated results are compared to experimental data in the cases of the ferromagnetic semiconductors EuO and Ga1-xMnxAs over a wide temperature range. For these materials the values 0.223 and 1.4 eV are evaluated for the exchange interaction parameter, respectively. A new feature is found in the ferromagnetic region, as a result of the exceptionally strong exchange interaction in Ga1-xMnxAs, i.e., a blue-shift in the band edge with decreasing temperature or with increasing

AB - We develop the theory of the shift in the band edge caused by a strong exchange interaction between charge carrier spins and the spins of the localized magnetic electrons in ferromagnetic semiconductors. The one-particle Green function is derived by using Matsubara's temperature Green functions, and then an infinite-order correction to the band edge due to the exchange interaction is determined from the poles of the Green function. With the aid of the temperature- and magnetic field-dependent spin polarization of the magnetic moments and the spin correlation functions, the band edge can be calculated as a function of temperature in various magnetic fields. The calculated results are compared to experimental data in the cases of the ferromagnetic semiconductors EuO and Ga1-xMnxAs over a wide temperature range. For these materials the values 0.223 and 1.4 eV are evaluated for the exchange interaction parameter, respectively. A new feature is found in the ferromagnetic region, as a result of the exceptionally strong exchange interaction in Ga1-xMnxAs, i.e., a blue-shift in the band edge with decreasing temperature or with increasing

KW - magnetic semiconductors

KW - ferromagnetic materials

KW - band gap blue shift

KW - band shift

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DO - 10.1088/0953-8984/14/17/319

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JF - Journal of Physics: Condensed Matter

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