Our ab initio theory calculations predict a semiconducting band structure of I-Mn-V compounds. We demonstrate on LiMnAs that high-quality materials with group-I alkali metals in the crystal structure can be grown by molecular beam epitaxy. Optical measurements on the LiMnAs epilayers are consistent with the theoretical electronic structure…
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We report the experimental observation of the spin-Hall effect in a 2D hole system with spin-orbit
coupling. The 2D hole layer is a part of a p-n junction light-emitting diode with a specially designed coplanar geometry which allows an angle-resolved polarization detection at opposite edges of the 2D hole system. In equilibrium the angular momenta of the spin-orbit split heavy-hole states lie in the plane of the 2D layer. When an electric field is applied across the hole channel, a nonzero out-of-plane component of the angular momentum is detected whose sign depends on the sign of the electric field and is opposite for the two edges. Microscopic quantum transport calculations show only a weak effect of disorder, suggesting that the clean limit spin-Hall conductance description (intrinsic spin-Hall effect) might apply
to our system.
We describe a new effect in semiconductor spintronics that leads to
dissipationless spin-currents in paramagnetic spin-orbit coupled systems.
We argue that in a high mobility two-dimensional electron
system with substantial Rashba spin-orbit coupling, a spin-current
that flows perpendicular to the charge current is intrinsic.
In the usual case where both spin-orbit split bands
are occupied, the intrinsic spin-Hall conductivity has a universal
value for zero quasiparticle spectral broadening.
We study the dc transport properties of (Ga,Mn)As diluted magnetic
semiconductors with Mn concentration varying from 1.5% to 8%.
Transport data obtained at low temperatures are discussed theoretically
within a model of band-hole quasiparticles with a finite
spectral width due to elastic scattering from Mn and compensating defects.
The quantitative understanding of dc magneto-transport effects
in (Ga,Mn)As is unparalleled in itinerant ferromagnetic systems.
We present a theory of the anomalous Hall effect in ferromagnetic (III,
Mn)V semiconductors. Our theory relates the anomalous Hall conductance
of a homogeneous ferromagnet to the Berry phase acquired by a
quasiparticle wave function upon traversing closed paths on the
spin-split Fermi surface. The quantitative agreement between our theory
and experimental data in both (In, Mn)As and (Ga, Mn)As systems suggests
that this disorder independent contribution to the anomalous Hall
conductivity dominates in diluted magnetic semiconductors…
We developed a mean-field theory of carrier-induced ferromagnetism in
diluted magnetic semiconductors. Our approach represents an improvement
over the standard Ruderman-Kittel-Kesuya-Yosida model allowing spatial
inhomogeneity of the system, free-carrier spin polarization, finite
temperature, and free-carrier exchange and correlation to be accounted
for self-consistently…
We report evidence for first-order phase
transitions in quantum Hall states (ν = 2, 4) confined to a wide
gallium arsenide quantum well. We observe hysteresis and an anomalous
temperature dependence in the longitudinal resistivity, indicative of
a transition between two distinct ground states of an Ising quantum
Hall ferromagnet.
