The influence ofδ-<Mn>-layer's magnetization on polarization of photoluminescence of quantum well in singular and vicinal InGaAs/GaAs/δ-<Mn> heterostructures

Abstract

The influence of δ-<Mn>-layer's magnetization on polarization of photoluminescence of quantum well in singular and vicinal InGaAs/GaAs/δ-<Mn> heterostructures Abstract. Magneto-optical properties and spin dynamics in a p-type GaAs-based heterostructures containing an InGaAs quantum well and 2 nm thick GaAs layer doped with 5 at. % Mn (GaAs:Mn) on flat and vicinal substrates were studied between 2 and 300 K. A significant enhancement of photoluminescence circular polarization P C = 15 % was found at temperatures T < 30 K. In the non-magnetic quantum well P C = 0 %. The polarization of the InGaAs quantum well photoluminescence follows the temperature dependence of the GaAs:Mn layer magnetization. Two types of ferromagnetism were found. In the heterostructures grown on the flat substrate parallel to the (001) GaAs plane the magnetization obeys the Bloch T 3/2 temperature dependence while for the structures grown on the vicinal surface (disoriented by 3°) the magnetization follows percolation dependence. The later is attributed to the formation of strongly disordered islands of GaAs:Mn. IntroductionHeterostructures containing a quantum well and a thin layer of a diluted magnetic semiconductor (DMS) like GaAs:Mn have attracted great attention due to their possible application for injecting spin-polarized carriers in light emitting diodes [1]. The implantation of Mn into the quantum well leads to low mobility of charge carriers and suppresses radiative recombination [2]. The spatial separation of charge carriers and the GaAs:Mn layer results in a considerable increase in the mobility of charge carriers and the luminescence quantum yield [3]. This combination of optically and magnetically active structures appears promising for controlling optical properties by spin-dependent magnetic field control over the luminescence.The presence of charge carriers in the GaAs:Mn layer facilitates the indirect Ruderman-KittelKasuya-Yosida (RKKY) exchange interaction between Mn 2+ ions in hybrid structures [4][5][6][7][8]. Measurements of the luminescence polarization [8], the electric resistance and the Hall voltage [4][5][6][7] indirectly confirmed the existence of ferromagnetism in GaAs:Mn layers. The interpretation of the magnetization data, however, is difficult and usually requires additional assumptions for the separation of the contributions of the diamagnetic crystal lattice and paramagnetic structural defects, substrate, and interlayer boundaries. This problem can be solved by the electron spin resonance (ESR) technique [9] allowing the separation of contributions of above mentioned subsystems to the magnetic susceptibility of the samples.

Defect induced ferromagnetic ordering in epitaxial Zn0.95Mn0.05O films on sapphire (0 0 0 1)

“…The temper ature-dependent magnetization in the field-cooled (FC) and zero-field-cooled (ZFC) curves for the ZMO epitaxial layer with H = 50 Oe are shown in figure 1(b). Both curves show the characteristics of percolation FM ordering, [16,17] which assumes the indirect exchange interaction between the magn etic ions and the charge carriers induces the local FM ordering in the crystal regions. The temperature-dependent magnetization difference (ΔM = M FC − M ZFC ) is particularly useful for discriminating small degrees of FM ordering in a large diamagnetic and/or paramagnetic background [18,19].…”