TY - JOUR
T1 - Magnetotransport properties of ferromagnetic semiconductor GaMnAs-based superlattices
AU - Lee, Sanghoon
AU - Chung, Sunjae
AU - Lee, Sangyeop
AU - Lee, Hakjoon
AU - Yoo, Taehee
AU - Liu, X.
AU - Furdyna, J. K.
N1 - Funding Information:
This research was supported by the Converging Research Center Program through the Ministry of Education, Science and Technology ( 2011K000786 ); by the National Research Foundation of Korea (NRF) Grant funded by the Government of Korea (MEST) (No. 2010-0025880 ); and by the National Science Foundation Grant DMR10-05851 .
PY - 2012/9
Y1 - 2012/9
N2 - Two series of GaMnAs/GaAs superlattices (SSs) comprised of ferromagnetic semiconductor GaMnAs layers and non-magnetic GaAs spacers were investigated by the electronic transport measurements with an external magnetic field applied in the plane of the sample. The two SL series consisted of specimens that were structurally the same, but the GaAs spacers layers of one series were doped by Be, while in the second series the spacers were undoped. Although in field scans taken at 4 K all SLs showed a typical anisotropic magnetoresistance (MR) behavior dominated by magnetic anisotropy, similar to that normally observed in single GaMnAs ferromagnetic layers grown on GaAs (001) substrates, some of the SLs showed signatures of interaction between the GaMnAs layers in the form of broadening of the MR hysteresis. The effect of inter-layer exchange coupling (IEC) between the GaMnAs magnetic layers became clear in the MR data taken at 30 K, where the strength of the magnetic anisotropy was reduced to the level of the inter-layer interaction. Specifically, MR measurements on two of the Be-doped SLs (BD2 and BD3) exhibited conspicuously large values of resistance at zero field, along with transitions of magnetization with negative coercive fields. The observation of these features in GaMnAs/GaAs SLs indicates the presence of spontaneous antiferromagnetic (AFM) inter-layer exchange coupling (IEC) between the GaMnAs magnetic layers. The study further revealed that the IEC in the GaMnAs multilayers strongly depended on the properties of the non-magnetic GaAs spacers, such as their thickness and the density of carriers in the layers. Importantly, these IEC effects occurred on a longer range than that expected from current theoretical studies.
AB - Two series of GaMnAs/GaAs superlattices (SSs) comprised of ferromagnetic semiconductor GaMnAs layers and non-magnetic GaAs spacers were investigated by the electronic transport measurements with an external magnetic field applied in the plane of the sample. The two SL series consisted of specimens that were structurally the same, but the GaAs spacers layers of one series were doped by Be, while in the second series the spacers were undoped. Although in field scans taken at 4 K all SLs showed a typical anisotropic magnetoresistance (MR) behavior dominated by magnetic anisotropy, similar to that normally observed in single GaMnAs ferromagnetic layers grown on GaAs (001) substrates, some of the SLs showed signatures of interaction between the GaMnAs layers in the form of broadening of the MR hysteresis. The effect of inter-layer exchange coupling (IEC) between the GaMnAs magnetic layers became clear in the MR data taken at 30 K, where the strength of the magnetic anisotropy was reduced to the level of the inter-layer interaction. Specifically, MR measurements on two of the Be-doped SLs (BD2 and BD3) exhibited conspicuously large values of resistance at zero field, along with transitions of magnetization with negative coercive fields. The observation of these features in GaMnAs/GaAs SLs indicates the presence of spontaneous antiferromagnetic (AFM) inter-layer exchange coupling (IEC) between the GaMnAs magnetic layers. The study further revealed that the IEC in the GaMnAs multilayers strongly depended on the properties of the non-magnetic GaAs spacers, such as their thickness and the density of carriers in the layers. Importantly, these IEC effects occurred on a longer range than that expected from current theoretical studies.
KW - Ferromagnetic semiconductor
KW - GaMnAs
KW - Inter-layer exchange coupling
KW - Magnetoresistance
KW - Superlattice
UR - http://www.scopus.com/inward/record.url?scp=84867500098&partnerID=8YFLogxK
U2 - 10.1016/j.cap.2012.02.014
DO - 10.1016/j.cap.2012.02.014
M3 - Article
AN - SCOPUS:84867500098
VL - 12
SP - S31-S36
JO - Current Applied Physics
JF - Current Applied Physics
SN - 1567-1739
IS - SUPPL. 2
ER -