Low-temperature molecular beam epitaxy allows one to dope GaAs with Mn over its solubility limit, making it possible to realize a III–V-based diluted magnetic semiconductor (Ga,Mn)As. Magnetization measurements revealed that (Ga,Mn)As is ferromagnetic at low temperatures. The ferromagnetic transition temperature Tc can be as high as 110 K for 5% Mn. Magnetotransport properties of (Ga,Mn)As were found closely related to its magnetic properties. The temperature and magnetic-field B dependence of resistivity ρ can be understood in terms of spin-dependent scattering. The p–d exchange determined from the B dependence of ρ is shown to be consistent with the exchange expected from Tc based on the Ruderman–Kittel–Kasuya–Yosida interaction. The anomalous Hall effect dominates the Hall resistance up to room temperature, allowing one to determine the magnetic properties from the magnetotransport measurements alone. Since (Ga,Mn)As can be grown pseudomorphically on GaAs, one can introduce ferromagnetism in GaAs-based heterostructures such as resonant tunneling diodes and observe spin-dependent phenomena in current–voltage characteristics. Magneto-optical properties of (Ga,Mn)As films are also presented.
The authors review the results of a wide variety of experiments on materials such as ${\mathrm{La}}_{2}{\mathrm{CuO}}_{4}$ and ${\mathrm{Nd}}_{2}{\mathrm{CuO}}_{4}$ that contain...
It is shown that the free energy of a volume V of an isotropic system of nonuniform composition or density is given by : NV∫V [f0(c)+κ(▿c)2]dV, where NV is the number of molecul...
We have produced ultrathin epitaxial graphite films which show remarkable 2D\nelectron gas (2DEG) behavior. The films, composed of typically 3 graphene\nsheets, were grown by th...
The aim of this paper is to advocate the usefulness of the spin-density-functional (SDF) formalism. The generalization of the Hohenberg-Kohn-Sham scheme to and SDF formalism is ...
Abstract The optical constants of amorphous Ge are determined for the photon energies from 0.08 to 1.6 eV. From 0.08 to 0.5 eV, the absorption is due to k ‐conserving transition...
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