A. Palevski

Tuning spin-orbit coupling and superconductivity at the SrTiO{3}/LaAlO{3} interface: a magnetotransport study.

The superconducting transition temperature T{c} of the SrTiO{3}/LaAlO{3} interface was varied by the electric field effect. The anisotropy of the upper critical field and the normal-state magnetotransport were studied as a function of gate voltage. The spin-orbit coupling energy epsilon{SO} is extracted. This tunable energy scale is used to explain the strong gate dependence of the mobility and of the anomalous Hall signal observed. Epsilon{SO} follows T{c} for the electric field range under study.

Shubnikov-de Haas oscillations in SrTiO3/LaAlO3 interface.

Quantum magnetic oscillations in SrTiO3/LaAlO3 interface are observed in the magnetoresistance. We study their frequency as a function of gate voltage and the evolution of their amplitude with temperature. The data are consistent with the Shubnikov-de Haas theory. The Hall resistivity ρ(xy) is nonlinear at low magnetic fields. ρ(xy) is fitted assuming multiple carrier contributions. We infer the density of the mobile charge carriers from the oscillations frequency and from Hall measurements. The comparison between these densities suggests multiple valley and spin degeneracy. The small amplitude of the oscillation is discussed in the framework of the multiple band scenario.

Shubnikov–De Haas Oscillations inSrTiO3/LaAlO3Interface

Quantum magnetic oscillations in SrTiO3/LaAlO3 interface are observed in the magnetoresistance. We study their frequency as a function of gate voltage and the evolution of their amplitude with temperature. The data are consistent with the Shubnikov-de Haas theory. The Hall resistivity ρ(xy) is nonlinear at low magnetic fields. ρ(xy) is fitted assuming multiple carrier contributions. We infer the density of the mobile charge carriers from the oscillations frequency and from Hall measurements. The comparison between these densities suggests multiple valley and spin degeneracy. The small amplitude of the oscillation is discussed in the framework of the multiple band scenario.

Oscillations of the Superconducting Critical Current in Nb-Cu-Ni-Cu-Nb Junctions

We report on experimental studies of superconductor-ferromagnet layered structures. Strong oscillations of the critical supercurrent were observed with the thickness variation of the ferromagnet. Using known microscopic parameters of Ni, we found reasonable agreement between the period of oscillations and the decay of the measured critical current, and theoretical calculations.

Anisotropic magneto-transport effects at SrTiO3\LaAlO3 interfaces

a two dimensional electron gas isformed at the interface between these insulators [1]. Thisinterface was latter shown to be superconducting [2] andmagnetic [3]. Recently Caviglia et al. have shown thatthe superconducting transition temperature can be con-trolled by solely varying the number of charge carriers atthe interface using a gate voltage.[4] These unexpectedresults and the potential for development of high per-formance oxide based electronics motivated an effort tounderstand the properties of this interface [5, 6, 7] andto improve it.The origin of the large carrier concentration at the in-terface remains under debate. When depositing mono-layers of LaAlO

Emerging weak localization effects on a topological insulator--insulating ferromagnet (Bi

Thin films of topological insulator Bi2Se3 were deposited directly on insulating ferromagnetic EuS. Unusual negative magnetoresistance was observed near the zero field below the Curie temperature (TC), resembling the weak localization effect; whereas the usual positive magnetoresistance was recovered above TC. Such negative magnetoresistance was only observed for Bi2Se3 layers thinner than t � 4nm, when its top and bottom surfaces are coupled. These results provide evidence for a proximity effect between a topological insulator and an insulating ferromagnet, laying the foundation for future realization of the half-integer quantized anomalous Hall effect in three-dimensional topological insulators.

_{2}

Abstract Many device structures benefit from the ability to selectively deposit epitaxial materials. Through the use of a masking material, such as Si3N4 or SiO2, on the substrate surface, patterns generated through standard lithographic procedures can be used to define regions for selective deposition. Highly selective growth can be achieved through the use of growth precursors which contain halogens, such as (C2H5)2GaCl and (C2H5)2AlCl. These compounds decompose, most probably, to the volatile mono-halogen species, e.g. GaCl, and also generate HCl in the gas phase as a reaction by-product. We present experimental results on the morphology and growth behavior of GaAs, AlxGa1−xAs, and InxGa1−xAs using this selective epitaxy technique. Electri cal and optical characterization has been carried out on these materials and selectively grown structures produced by this technique. The interface between the selectively grown material and the underlying substrate was investigated and the conditions for achieving high quality electrical interfaces were determined. A thermodynamic model of this growth chemistry predicts the trends in composition and growth rate. The thermodynamic model, based on the quasi-equilibrium of the halogen-based compounds with the substrate surface, indicates that the growth behavior is very similar to the inorganic-based growth of these compounds. Experimental applications of this technique to high speed digital device structures and sub-micron dimensioned optical structures are presented.

Se

We report complementary studies of the critical temperature and the critical current in ferromagnet (Ni) - superconductor (Nb) multilayers. The observed oscillatory behavior of both quantities upon variation of the thickness of the ferromagnetic layer is found to be in good agreement with theory. The length scale of oscillations is identical for both quantities and is set by the magnetic length corresponding to an exchange field of 200 meV in Ni. The consistency between the behavior of the two quantities provides strong evidence for periodic pi phase shifts in these devices.

_{3}

The evolution of microstructure in Al and Cu thin film lines during electromigration has been studied using a transmission electron microscopy. Grain boundary migration was found to be critically involved in the electromigration induced hillock formation that can be described as a three‐dimensional growth of a single grain.

-EuS) interface

The search for broken time-reversal symmetry (time-reversal symmetry breaking (TRSB)) in unconventional superconductors has intensified in the past few years as more systems have been predicted to possess such a state. Following our pioneering study of TRSB states in Sr2RuO4 using magneto-optic probes, we embarked on a systematic study of several other of these candidate systems. The primary instrument for our studies is the Sagnac magneto-optic interferometer that we recently developed. This instrument can measure magneto-optic Faraday or Kerr effects with an unprecedented sensitivity of 10 nrad at temperatures as low as 100 mK. In this paper, we review our recent studies of TRSB in several systems, emphasizing the study of the pseudogap state of high temperature superconductors and the inverse proximity effect in superconductor/ferromagnet proximity structures.