Nathaniel P. Stern

Current-induced polarization and the spin Hall effect at room temperature.

Electrically induced electron spin polarization is imaged in n-type ZnSe epilayers using Kerr rotation spectroscopy. Despite no evidence for an electrically induced internal magnetic field, current-induced in-plane spin polarization is observed with characteristic spin lifetimes that decrease with doping density. The spin Hall effect is also observed, indicated by an electrically induced out-of-plane spin polarization with opposite sign for spins accumulating on opposite edges of the sample. The spin Hall conductivity is estimated as 3+/-1.5 Omega(-1) m(-1)/|e| at 20 K, which is consistent with the extrinsic mechanism. Both the current-induced spin polarization and the spin Hall effect are observed at temperatures from 10 to 295 K.

Structural, electrical, and magneto-optical characterization of paramagnetic GaMnAs quantum wells

The growth of GaMnAs by molecular beam epitaxy is typically performed at low substrate temperatures

Strong interactions of single atoms and photons near a dielectric boundary

(\ensuremath{\sim}250\phantom{\rule{0.2em}{0ex}}\ifmmode^\circ\else\textdegree\fi{}\mathrm{C})

Antiferromagnetic s-d exchange coupling in GaMnAs

and high As overpressures, leading to the incorporation of excess As and Mn interstitials, which quench optical signals such as photoluminescence (PL). We report on optical-quality

A state-insensitive, compensated nanofiber trap

{\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}\mathrm{As}∕{\mathrm{Al}}_{0.4}{\mathrm{Ga}}_{0.6}\mathrm{As}

Valley-polarized exciton–polaritons in a monolayer semiconductor

quantum wells (QWs) with

Drift and diffusion of spins generated by the spin Hall effect

xl0.2%

Coherent optical non-reciprocity in axisymmetric resonators

grown at a substrate temperature of

Confinement engineering of s-d exchange interactions in Ga1-x Mnx As/Aly Ga1-y As quantum wells

400\phantom{\rule{0.2em}{0ex}}\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}

Spin transfer and coherence in coupled quantum wells

. Electrical and structural measurements demonstrate that this elevated temperature reduces As defects while allowing the substitutional incorporation of Mn into Ga sites. From a combination of Hall and secondary ion mass spectroscopy measurements we estimate that at least 70%--90% of the Mn incorporates substitutionally in all samples studied. The incorporation behavior shows both a substrate temperature and QW width dependence. The low defect density of these heterostructures, compared to typical lower-temperature-grown GaMnAs, enables the observation of both polarization-resolved PL and coherent electron spin dynamics, from which the conduction-band exchange parameter is extracted. No evidence of long-range Mn spin coupling is observed, whereas negative effective Curie temperatures indicate spin heating due to photoexcitation. Light Mn doping maximizes the electron spin lifetime, indicating the importance of the Dyakonov-Perel decoherence mechanism in these structures. PL spectra reveal a low-energy peak from shallow donors, which, because of the paramagnetic behavior of its PL polarization, we ascribe to Mn interstitials.