-
The identification of the dominant donors in low temperature grown InPBi materials
Authors:
G. N. Wei,
D. Xing,
Q. Feng,
W. G. Luo,
Y. Y. Li,
K. Wang,
L. Y. Zhang,
W. W. Pan,
S. M. Wang,
S. Y. Yang,
K. Y. Wang
Abstract:
Combined with magnetotransport measurements and first-principles calculations, we systematically investigated the effects of Bi incorporation on the electrical properties of the undoped InP1-xBix epilayers with 0<x<2.41%. The Hall-bar measurements reveal a dominant n-type conductivity of the InPBi samples. The electron concentrations are found to decrease firstly as x increases up to x=1.83%, and…
▽ More
Combined with magnetotransport measurements and first-principles calculations, we systematically investigated the effects of Bi incorporation on the electrical properties of the undoped InP1-xBix epilayers with 0<x<2.41%. The Hall-bar measurements reveal a dominant n-type conductivity of the InPBi samples. The electron concentrations are found to decrease firstly as x increases up to x=1.83%, and then increase again with further increasing Bi composition, whiles the electron mobility shows an inverse variation to the electron concentration. First-principle calculations suggest that both the phosphorus antisites and vacancy defects are the dominant donors responsible for the high electron concentration. And their defect concentrations show different behaviors as Bi composition x increases, resulting in a nonlinear relationship between electron concentration and Bi composition in InPBi alloys.
△ Less
Submitted 29 March, 2016;
originally announced March 2016.
-
Bismuth-content dependent of the polarized Raman spectra of the InPBi alloys
Authors:
G. N. Wei,
T. Q. Hai,
Q. Feng,
D. Xing,
W. G. Luo,
K. Wang,
L. Y. Zhang,
S. M. Wang,
K. Y. Wang
Abstract:
We have systematically investigated the optical properties of the InP1-xBix ternary alloys with 0<x<2.46%, using high resolution polarized Raman scattering measurement. Both InP-like and InBi-like optical vibration modes (LO) were identified in all the samples, suggesting most of the Bi-atoms are incorporated into the lattice sites to substitute P-atoms. And the intensity of the InBi-like Raman mo…
▽ More
We have systematically investigated the optical properties of the InP1-xBix ternary alloys with 0<x<2.46%, using high resolution polarized Raman scattering measurement. Both InP-like and InBi-like optical vibration modes (LO) were identified in all the samples, suggesting most of the Bi-atoms are incorporated into the lattice sites to substitute P-atoms. And the intensity of the InBi-like Raman modes increase exponentially as Bi-content increasing. Linearly red-shift of the InP-like longitudinal optical vibration modes was observed to be 1.1 cm-1 of percent Bi, while that of the InP-like optical vibration overtones (2LO) were nearly doubled. In addition, through comparing the difference between the Z(X,X)Z and Z(X,Y)Z Raman spectra, Longitudinal Optical Plasmon Coupled (LOPC) modes are identified in all the samples, and their intensities are found to be proportional to the electron concentrations.
△ Less
Submitted 14 December, 2015;
originally announced December 2015.
-
Longitudinal Spin Seebeck Effect in Silver Strip on CoFe Film
Authors:
Y. Sheng,
M. Y. Yang,
Y. Cao,
K. M. Cai,
G. N. Wei,
G. H. Yu,
B. Zhang,
X. Q. Ma,
K. Y. Wang
Abstract:
We report the experimental observation of the spin Seebeck effect (SSE) in Ag/CoFe noble metal/magnetic metal bilayers with a longitudinal structure. Thermal voltages jointly generated by the anomalous Nernst effect (ANE) and the SSE were detected across the Ag/CoFe/Cu strip with a perpendicular thermal gradient. To effectively separate the SSE and the ANE part of the thermal voltages, we compared…
▽ More
We report the experimental observation of the spin Seebeck effect (SSE) in Ag/CoFe noble metal/magnetic metal bilayers with a longitudinal structure. Thermal voltages jointly generated by the anomalous Nernst effect (ANE) and the SSE were detected across the Ag/CoFe/Cu strip with a perpendicular thermal gradient. To effectively separate the SSE and the ANE part of the thermal voltages, we compared the experimental results between the Ag/CoFe/Cu strip and Cu/CoFe/Cu strip, where two samples processed with the heating power instead of the temperature difference through the thin CoFe film. The respective contributions of the ANE and SSE to thermal voltage were determined, and they have the ratio of 4:1. The spin current injected through CoFe/Ag interface is calculated to be 1.76 mA/W.
△ Less
Submitted 28 October, 2015;
originally announced October 2015.
-
Magnetic Coupling in Ferromagnetic Semiconductor GaMnAs/AlGaMnAs Bilayer Devices
Authors:
Y. F. Cao,
Yanyong Li,
Yuanyuan Li,
G. N. Wei,
Y. Ji,
K. Y. Wang
Abstract:
We carefully investigated the ferromagnetic coupling in the as-grown and annealed ferromagnetic semiconductor GaMnAs/AlGaMnAs bilayer devices. We observed that the magnetic interaction between the two layers strongly affects the magnetoresistance of the GaMnAs layer with applying out of plane magnetic field. After low temperature annealing, the magnetic easy axis of the AlGaMnAs layer switches fro…
▽ More
We carefully investigated the ferromagnetic coupling in the as-grown and annealed ferromagnetic semiconductor GaMnAs/AlGaMnAs bilayer devices. We observed that the magnetic interaction between the two layers strongly affects the magnetoresistance of the GaMnAs layer with applying out of plane magnetic field. After low temperature annealing, the magnetic easy axis of the AlGaMnAs layer switches from out of plane into in-plane and the interlayer coupling efficiency is reduced from up to 0.6 to less than 0.4. However, the magnetic coupling penetration depth for the annealed device is twice that of the as-grown bilayer device.
△ Less
Submitted 23 January, 2015;
originally announced January 2015.
-
Anisotropic Current-Controlled Magnetization Reversal in the Ferromagnetic Semiconductor (Ga,Mn)As
Authors:
Yuanyuan Li,
Y. F. Cao,
G. N. Wei,
Yanyong Li,
Y. Ji,
K. Y. Wang,
K. W. Edmonds,
R. P. Campion,
A. W. Rushforth,
C. T. Foxon,
B. L. Gallagher
Abstract:
Electrical current manipulation of magnetization switching through spin-orbital coupling in ferromagnetic semiconductor (Ga,Mn)As Hall bar devices has been investigated. The efficiency of the current-controlled magnetization switching is found to be sensitive to the orientation of the current with respect to the crystalline axes. The dependence of the spin-orbit effective magnetic field on the dir…
▽ More
Electrical current manipulation of magnetization switching through spin-orbital coupling in ferromagnetic semiconductor (Ga,Mn)As Hall bar devices has been investigated. The efficiency of the current-controlled magnetization switching is found to be sensitive to the orientation of the current with respect to the crystalline axes. The dependence of the spin-orbit effective magnetic field on the direction and magnitude of the current is determined from the shifts in the magnetization switching angle. We find that the strain induced effective magnetic field is about three times as large as the Rashba induced magnetic field in our GaMnAs devices.
△ Less
Submitted 8 March, 2013;
originally announced March 2013.