As and Epitaxial-Growth MnSi Thin Films - OPUS Würzburg

26 3. Electric Control of Magnetization in Thin (Ga,Mn)As Layers
4 nm
1.4 nm x Mn
LT GaAs (Ga,Mn)As HT GaAs + GaAs
[001] substrate
Fig. 3.1: Schematic diagram of the bulk4-nm andparabolic-doped ultrathin (Ga,Mn)As layers.
A total thickness of 4nm is calculated for the DMS region of the parabolic layer, with the highest
doping concentration at the center (1.4 nm (Ga,Mn)As layer.) The samples are grown using
low-temperature MBE.
appendix A. For the Hall bar, we used a layer with Mn concentration of ≈ 1.8% and the
Corbino x Mn ≈ 2%, both values extracted by SQUID measurements. To test the electrical
and magnetotransport properties of the sample, a He-cooled cryostat with an XYZ
vector magnet with maximum resultant field of 300 mT is used. The AC measurements
are done using a standard lock-in (EGG Stanford Research Systems Model 124 analog
lock-in amplifier) setup at 13Hz.
Fig. 3.2: Schematic diagram of the all-semiconductor p-n junction gating structure based on
[Owen 09]. The (Ga,Mn)As channel in our experiments is theparabolic-doped (Ga,Mn)As layer.