Spin Excitations of the Spin-Polarized Electron Gas in Semimagnetic Quantum Wells

Abstract

Collective and single-particle spin-flip excitations of a two-dimensional electron gas in a semimagnetic Cd(1-x)Mn(x)Te quantum well are observed by resonant Raman scattering. Application of a magnetic field splits the spin subbands and a spin polarization is induced in the electron gas. Above 1 T the collective modes, which disperse with the in-plane wave vector, dominate the spectra. The local spin-density approximation provides a good description of our results and enables us to confirm that the energy of the low wave vector collective mode is given by the bare Zeeman energy.

Intrinsic damping of spin waves by spin current in conducting two-dimensional systems

“…Since, the well defined spin waves modes has been successfully observed in these quantum wells 8 , this material is a perfect candidate to investigate the damping.…”

“…ERRS is a powerful tool to access wavevector resolution of the spin excitations spectrum 8 . Over the last decades, general knowledge on electron gases low-energy excitations has been considerably improved by ERRS study of high mobility unpolarized 2DEG 12 .…”

Spin waves in diluted magnetic quantum wells

“…Our studies are motivated by recent experiments [5][6][7] and a theoretical discussion [7][8][9] focused on the spin dynamics in diluted magnetic Cd 1−x Mn x Te quantum wells placed into the magnetic field [10]. In Ref.…”

“…It was demonstrated that the excitations exist in a finite range of wavelengths, k < k m , and their group velocity is negative: dω(k)/dk < 0. The experimental data were interpreted [5,8] in terms of conventional spin waves in the Fermi liquids [11], while k m was attributed to the edge of the Stoner continuum of the single-particle spin excitations. Such interpretation implies that the only effect of the magnetic ions on the electron spin waves is the strong renormalization of the electron Zeeman splitting.…”

“…In Ref. 5, the spectrum of the spin waves, ω(k), was measured. Only one excitation mode was observed.…”