The formation of vortices by topological phase engineering has been realized experimentally to create the first two- and four-quantum vortices in dilute atomic Bose-Einstein condensates. We consider a similar system, but in addition to the Ioffe-Pritchard magnetic trap we employ an additional hexapole field. By controlling cyclically the strengths of these magnetic fields, we show that a fixed ...

Using an asymptotic solution of the M -impurity thermodynamics of a dilute s-d system, the impurity energy and impurity heat capacity ∆C(T ) are derived for dilute magnetic alloys with spin 1/2 and spin 3/2 impurities. The parameters which enter ∆C are adjusted to fit experimental data on impurity heat capacity of CuCr and (La1−xCex) Al2. Agreement is satisfactory for CuCr, at temperatures belo...

We report transport studies on magnetically doped Bi(2)Se(3) topological insulator ultrathin films grown by molecular beam epitaxy. The magnetotransport behavior exhibits a systematic crossover between weak antilocalization and weak localization with the change of magnetic impurity concentration, temperature, and magnetic field. We show that the localization property is closely related to the m...

We study the changes of magnetoresistance induced by controlled thermal annealing at temperatures ranging from 300 to 600 °C of a Ga0.98Mn0.02As alloy grown by low-temperature molecular beam epitaxy. We use a resistor-network model for describing the electrical transport as a function of temperature and external magnetic field. The model is founded on classical semiconductor band transport and ...

There is much interest and debate concerning the origin of ferromagnetism in dilute alloys of MnxGa1-xAs and other magnetically doped semiconductors [1]. The Mn acts as an acceptor introducing itinerant holes into the semiconductor. The ferromagnetic (FM) coupling between the magnetic Mn is thought to be via RKKY screening by the itinerant hole gas [2]. This coupling induces FM order at concent...

We report the first example of a dilute magnetic semiconductor (DMS) confined in all three dimensions (DMS quantum dot). Zn0.93Mn0.07S clusters o f 2 5 A diameter are successfully synthesized inside a glass matrix and fully characterized by chemical analysis, x-ray diffraction, extended x-ray absorption fine structure (EXAFS), and photoluminescence spectroscopy. Effect of size quantization on t...

Bose-Einstein condensation in a dilute gas of sodium atoms has been observed. The atoms were trapped in an optically plugged magnetic trap or in a cloverleaf magnetic trap. Rf induced evaporative cooling increased the phase-space density by six orders of magnitude. We summarize the different techniques used, and discuss recent studies of properties of Bose condensates with an outlook on future ...

A GaMnAs nanoelectromechanical resonator is used to obtain the first measurement of magnetostriction in a dilute magnetic semiconductor. Resonance frequency shifts induced by field-dependent magnetoelastic stress are used to simultaneously map the magnetostriction and magnetic anisotropy constants over a wide range of temperatures. Owing to the central role of carriers in controlling ferromagne...