Spin diffusion in theMn2+ion system of II-VI diluted magnetic semiconductor heterostructures

Abstract

The magnetization dynamics in diluted magnetic semiconductor heterostructures based on (Zn,Mn)Se and (Cd,Mn)Te has been studied experimentally by optical methods and simulated numerically. In the samples with nonhomogeneous magnetic ion distribution this dynamics is contributed by spin-lattice relaxation and spin diffusion in the Mn spin system. The spin diffusion coefficient of 7 · 10 −8 cm 2 /s has been evaluated for Zn0.99Mn0.01Se from comparison of experimental and numerical results. Calculations of the giant Zeeman splitting of the exciton states and the magnetization dynamics in the ordered alloys and parabolic quantum wells fabricated by the digital growth technique show perfect agreement with the experimental data. In both structure types the spin diffusion has an essential contribution to the magnetization dynamics.

Influence of nonmagnetic impurity scattering on spin dynamics in diluted magnetic semiconductors

“…An exponential fit to the dynamics of the full quantum kinetic theory yields an effective spin transfer rate about 15% smaller than the Markovian rate in Eq. (15).…”

“…For this purpose, spintronic devices based on semiconductors are preferable to metallic structures since the dephasing time in a metal is about three orders of magnitude shorter than in a semiconductor 4 . In the context of semiconductor spintronics [5][6][7] , a particularly interesting class of materials for future applications are diluted magnetic semiconductors (DMS) [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] , which are obtained when semiconductors are doped with transition metal elements, such as Mn, which act as localized magnetic moments. While some types of DMS, such as Ga 1−x Mn x As, exhibit a ferromagnetic phase 8,23 , other types of DMS, like the usually paramagnetic CdMnTe, are especially valued for the enhancement of the effective carrier g-factor by the giant Zeeman effect that can be used, e.g., to facilitate an injection of a spin-polarized current into a light-emitting diode 24 .…”

Antiferromagnetic interaction in coupled CdSe/ZnMnSe quantum dot structures

“…Otherwise, the AFC effect would have ceased to exist after the lifetime of the DMS excitons that would have led the QD PL polarization returning back to the value under the quasi-resonant excitation. Besides the DMS exciton spins, spins of the Mn ions in the DMS can also be aligned under the optical excitation at the r þ active DMS exciton state at 5 T. As spin dynamics of the Mn ions is known to be relatively slow, in order of 1 ls in DMS with a similar Mn content, 21 the spin-polarized Mn ions could effectively maintain their interaction with the QD exciton spins within the lifetime of the QD excitons (i.e., over the 1.5-ns time window in our TR-PL measurements). Therefore, the spin-aligned Mn ions in the DMS can be a plausible source of the enhancement in the QD PL and spin polarization.…”

Dynamical control of Mn spin-system cooling by photogenerated carriers in a (Zn,Mn)Se/BeTe heterostructure

“…The strong dependence of magnetization dynamics on the Mn concentration, 6 spin diffusion in heteromagnetic semiconductor structures, 7,8 and acceleration of SLR of Mn ions in the presence of free electrons 9,10 have been reported. The free electrons provide an additional channel for spin and energy transfer from the Mn spin system into the phonon bath ͑lattice͒, which can be considerably more efficient than the direct spin-lattice relaxation channel.…”