Non-Linearities in the Faraday Rotation and Absorption Due to Excitons in the Ferromagnetic Semiconductor CdCr2Se4

Golik, L. L.; Kun’kova, Z. E.

doi:10.1002/1521-3951(200006)219:2<411::aid-pssb411>3.0.co;2-a

Cited by 3 publications

(13 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It follows from comparison of the curves 1 and 3 that the FR band intensifies when measured with the probing laser. A change of the FR band shape also takes place, which was not observed earlier [12,13]. The FR growth (∆F ≈ 8° near the band maximum) displays that the probe intensity level used was already in the region of nonlinearity of the Faraday effect.…”

Section: Resultssupporting

confidence: 59%

“…It is clear that the photoinduced FR grows, as the pump power density P p increases. For comparison the dependence of the nonlinear FR (∆F n ) on incident radiation intensity measured in [13] is also shown in Fig. 2.…”

Section: Resultsmentioning

confidence: 99%

“…Dependence of the photoinduced Faraday rotation ∆F p on power density of the pump radiation (1) and dependence of the nonlinear FR ∆F n on incident radiation intensity (2). Curve 2 was taken from [13]. T, K: 1 -90; 2 -110. the same sample CdCr 2 Se 4 , which dependences F(hν) were represented in Fig.…”

Section: Figmentioning

confidence: 99%

“…A strong influence of intensive radiation of neodymium laser (λ = 1060 nm) on the magnitude of Faraday rotation (FR) in CdCr 2 Se 4 was observed [11]. Spectral dependences of the nonlinear FR and nonlinear absorption of circularly polarized light near the absorption edge of CdCr 2 Se 4 were researched in [12,13]. It was found that these nonlinear effects were associated with the resonant structure near the absorption edge, which was attributed by authors to the creation of excitons.…”

Section: Introductionmentioning

confidence: 99%

“…It was found that these nonlinear effects were associated with the resonant structure near the absorption edge, which was attributed by authors to the creation of excitons. Mechanisms of the screen-ing of internal electric fields and electron-hole interaction by photoexcited charge carriers, resulting in enhancement and attenuation of the excitonic resonance, respectively, were invoked to explain the nonlinear effects observed [12,13]. If the proposed explanation of the nonlinear FR is true, a considerable photoinduced Faraday rotation (a rotation of the polarization direction of a weak probe beam under the action of an intensive pump radiation) must be observed in CdCr 2 Se 4 also in the spectral region near the excitonic resonance.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Photoinduced Faraday rotation in the magnetic semiconductor CdCr2Se4

Golik

Kun’kova

2004

phys. stat. sol. (a)

View full text Add to dashboard Cite

A growth of the excitonic peak in the absorption spectrum and an enhancement of the Faraday rotation band (approximately 50% of the linear effect value) were induced by intensive radiation of Nd 3+ -laser (hν = 1.17 eV) in ferromagnetic phase of magnetic semiconductor CdCr 2 Se 4 . The photoinduced effects increased during a pumping pulse and also with growth of pump intensity. In studies of the non-linear Faraday rotation a change of the spectral band shape was observed along with the growth of the rotation angle. The observed effects can be explained by the screening of internal electric fields existing in CdCr 2 Se 4 crystals by photoexcited charge carriers.

show abstract

Section: Resultssupporting

confidence: 59%

Section: Resultsmentioning

confidence: 99%

Section: Figmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Photoinduced Faraday rotation in the magnetic semiconductor CdCr2Se4

Golik

Kun’kova

2004

phys. stat. sol. (a)

View full text Add to dashboard Cite

show abstract

Untitled

Karczewski

Sawicki

Ivanov

et al. 2003

Journal of Superconductivity

View full text Add to dashboard Cite

Spectral tunability of laser-induced spin dynamics in the ferromagnetic semiconductor CdCr2Se4

et al. 2018

View full text Add to dashboard Cite

Here we report that femtosecond laser pulses are able to trigger oscillations of the magneto-optical Faraday rotation in the ferromagnetic semiconductor CdCr 2 Se 4 in the presence of an applied magnetic field. The frequency of these oscillations is a linear function of the magnetic field and corresponds to the ferromagnetic resonance (FMR). Tuning the photon energy of the pump pulses we reveal two different mechanisms, which induce FMR precession in this material. In the case of pumping from the valence band deep into the conduction band (photon energy 3.1 eV), the phase of the spin oscillations is not sensitive to the polarization of the pump, but can be reversed over 180 deg by changing the polarity of the applied magnetic field. We assign these oscillations to the coherent spin precession triggered by ultrafast laser-induced heating. This mechanism requires a strong optical absorption in the material and becomes inactive if the pump photon energy is below the band gap. Tuning the photon energy in a wide range from 0.88 to 2.1 eV reveals the second mechanism of optical excitation of coherent spin oscillations with a maximum around 1.2 eV, i.e., very close to the energy of the band gap in the semiconductor. Contrary to the laser-induced heating, this excitation mechanism is pump polarization dependent, being the most efficient if the pump is circularly polarized. The phase of the spin oscillations is independent of the polarity of the applied magnetic field, but changes by 180 deg under reversing the helicity of light. We suggest that the effect can be interpreted in terms of spin transfer torque experienced by the network of the ordered Cr 3+ spins as a result of excitation of electrons from the top of the p-type valence band to the bottom of the s-type conduction band. In particular, a strong spin-orbit interaction experienced by the carriers in the valence band is responsible for the coupling of the spins of the photogenerated carriers and the polarization of light. Due to strong pdand sd-exchange interactions the spins of the photocarriers appear to be coupled to the network of ordered spins of the Cr 3+ ions.

show abstract

Non-Linearities in the Faraday Rotation and Absorption Due to Excitons in the Ferromagnetic Semiconductor CdCr2Se4

Cited by 3 publications

References 10 publications

Photoinduced Faraday rotation in the magnetic semiconductor CdCr2Se4

Photoinduced Faraday rotation in the magnetic semiconductor CdCr2Se4

Untitled

Spectral tunability of laser-induced spin dynamics in the ferromagnetic semiconductor CdCr2Se4

Contact Info

Product

Resources

About