A. M. Goldman

In situ formation of superconducting YBa2Cu3O7−x thin films using pure ozone vapor oxidation

Superconducting YBa2Cu3O7−x thin films have been prepared by coevaporation using an ozone vapor jet as an oxygen source. Films exhibiting zero resistance at 82 K have been fabricated in situ under high vacuum conditions using substrate temperatures of 700 °C without a post‐evaporation anneal in oxygen. This process has implications for in situ measurements of fully superconducting surfaces using a variety of probes as well as for the fabrication of devices and structures whose properties are dependent on surfaces and interfaces.

Cuprate/manganite heterostructures

Advances in thin film deposition techniques have made it possible to produce heterostructures of high-temperature superconducting compounds and manganite perovskites. The latter exhibit the phenomenon of colossal magnetoresistance (CMR). The half-metallic character of the CMR compounds results in their carriers being spin polarized. Experiments with these heterostructures have demonstrated that the injection of spin-polarized carriers into high-temperature superconductors results in a reduction of parameters such as the critical current and critical temperature. The experimental situation is reviewed, and open questions are identified.

Phase diagram of electrostatically doped SrTiO3.

Electric double layer transistor configurations have been employed to electrostatically dope single crystals of insulating SrTiO(3). Here we report on the results of such doping over broad ranges of temperature and carrier concentration employing an ionic liquid as the gate dielectric. The surprising results are, with increasing carrier concentration, an apparent carrier-density dependent conductor-insulator transition, a regime of the anomalous Hall effect, suggesting magnetic ordering, and finally the appearance of superconductivity. The possible appearance of magnetic order near the boundary between the insulating and superconducting regimes is reminiscent of effects associated with quantum critical behavior in some complex compounds.

Electrostatic tuning of the superconductor-insulator transition in two dimensions.

Superconductivity has been induced in insulating ultrathin films of amorphous bismuth using the electric field effect. The screening of the electron-electron interaction was found to increase with electron concentration in a manner correlated with the tendency towards superconductivity. This does not preclude an increase in the density of states being important in the development of superconductivity. The superconductor-insulator transition appears to belong to the universality class of the three dimensional XY model.

In situ growth of DyBa2Cu3O7−x thin films by molecular beam epitaxy

Films of DyBa2Cu3O7−x with transition temperatures as high as 89 K and with nominal thicknesses down to 35 A have been grown in situ using molecular beam epitaxy employing ozone as a source of reactive oxygen. The process has been successful with a variety of substrates including SrTiO3(100), SrTiO3(110), LaAlO3(100), MgO(100), and yttria‐stabilized zirconia. The films could be imaged with a scanning tunneling microscope at 4.2 K, indicating a conducting surface even at low temperatures.

Thickness–Magnetic Field Phase Diagram at the Superconductor-Insulator Transition in 2D

The superconductor-insulator transition in ultrathin films of amorphous Bi has been tuned by changing both film thickness and magnetic field on the same set of films. A thickness\char21{}magnetic field phase diagram has been mapped in the

High-temperature superconducting microbolometer

T\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0

Spin transport through multilayer graphene

limit. A finite size scaling analysis has been carried out to determine the critical exponent product

Oscillatory Exchange Coupling and Positive Magnetoresistance in Epitaxial Oxide Heterostructures

\ensuremath{\nu}z

Superconductor-insulator transitions

, which was found to be