Antiferromagnetic Interlayer Exchange Coupling in Ferromagnetic GaMnAs/GaAs:Be Multilayers

Abstract

Interlayer exchange coupling (IEC) between the GaMnAs layers in GaMnAs/GaAs:Be multilayer systems has been investigated using magnetotransport experiments. The observation of a stable antiparallel magnetization alignment state from the systems indicates the presence of antiferromagnetic (AFM) IEC between the GaMnAs layers. The transitions between parallel and antiparallel alignments of GaMnAs magnetic layers in the system were carefully investigated by measuring resistance change with increasing temperature under various bias magnetic fields. From the dependence of the transition temperature on bias fields, we have estimated the magnitude of AFM IEC and its temperature behavior of our GaMnAs/GaAs:Be multilayers.Index Terms-Interlayer exchange coupling (IEC), magnetic multilayers, magnetoresistance (MR).

Interlayer exchange coupling in (Ga,Mn)As ferromagnetic semiconductor multilayer systems

“…Measurements were performed at 30 K with current along the [1-10] direction (i.e., long dimension of the Hall device for sample series A and B) and the external field applied near the [110] crystallographic direction. The temperature of 30 K was selected in order to maximize IEC effect during the magnetization reversal process, which was dominated by crystalline anisotropy at low temperature [20][21][22][23] . The MR data are plotted in Fig.…”

“…Since the transition fields are all different for the (Ga,Mn)As layers in the multilayer system, the magnitude of the total IEC acting on each (Ga,Mn)As layer can be different. The magnitude of the IEC acting on each magnetic layer in [(Ga,Mn)As/GaAs:Be] 10 multilayer was investigated by Chung et al [21] , using a series of partial (minor) hysteresis loop experiments, in which magnetization reversal occurs only in specific (Ga,Mn)As layers, and not in others. The magnitudes of NN IEC for all (Ga,Mn)As layers obtained in that study lie in the range of 20 to 30 Oe, with the exception of the top (Ga,Mn)As layer, which is about twice as large as the values for the other (Ga,Mn)As layers.…”