1,738 research outputs found
Artificial control of the bias-voltage dependence of tunnelling anisotropic magnetoresistance using quantization in a single-crystal ferromagnet
A major issue in the development of spintronic memory devices is the
reduction of the power consumption for the magnetization reversal. For this
purpose, the artificial control of the magnetic anisotropy of ferromagnetic
materials is of great importance. Here, we demonstrate the control of the
carrier-energy dependence of the magnetic anisotropy of the density of states
(DOS) using the quantum size effect in a single-crystal ferromagnetic material,
GaMnAs. We show that the mainly two-fold symmetry of the magnetic anisotropy of
DOS, which is attributed to the impurity band, is changed to a four-fold
symmetry by enhancing the quantum size effect in the valence band of the GaMnAs
quantum wells. By combination with the gate-electric field control technique,
our concept of the usage of the quantum size effect for the control of the
magnetism will pave the way for the ultra-low-power manipulation of
magnetization in future spintronic devices.Comment: 9 pages, 7 figure
Properties and Curie Temperature (130 K) of Heavily Mn-doped Quaternary Alloy Ferromagnetic Semiconductor (InGaMn)As Grown on InP
We have studied magnetic properties of heavily Mn-doped
[(In0.44Ga0.56)0.79Mn0.21]As thin films grown by low-temperature molecular-beam
epitaxy (LT-MBE) on InP substrates. The (InGaMn)As with high Mn content (21%)
was obtained by decreasing the growth temperature to 190 degC. When the
thickness of the [(In0.44Ga0.56)0.79Mn0.21]As layer is equal or thinner than 10
nm, the reflection high-energy electron diffraction (RHEED) pattern and
transmission electron microscopy (TEM) show no MnAs clustering, indicating that
a homogeneous single crystal with good quality was grown. In the magnetic
circular dicroism (MCD) measurement, large MCD intensity and high Curie
temperature of 130 K were observed.Comment: 3 pages, 5 figure
Anomalous Fermi level behavior in GaMnAs at the onset of ferromagnetism
We present the systematic study of the resonant tunneling spectroscopy on a
series of ferromagnetic-semiconductor Ga1-xMnxAs with the Mn content x from
~0.01 to 3.2%. The Fermi level of Ga1-xMnxAs exists in the band gap in the
whole x region. The Fermi level is closest to the valence band (VB) at x=1.0%
corresponding to the onset of ferromagnetism near the metal-insulator
transition (MIT), but it moves away from the VB as x increasing or decreasing
from 1.0%. This anomalous behavior of the Fermi level indicates that the
ferromagnetism and MIT emerge in the Mn-derived impurity band.Comment: 4 pages, 4 figures, 1 table (minor revision
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