Publications de Guy Joseph Günter Dubuis

On Local Pairs vs. BCS: Quo Vadis High- T-c Superconductivity

Davor Pavuna, Guy Joseph Günter Dubuis, Ivan Bozovic, Xi He

Since the discovery of high-temperature superconductivity in cuprates, proposals have been made that pairing may be local, in particular in underdoped samples. Here, we briefly review evidence for local pairs from our experiments on thin films of La (2-x) ...

Springer2017

Oxygen Displacement in Cuprates under Ionic Liquid Field-Effect Gating

Davor Pavuna, Guy Joseph Günter Dubuis, Ivan Bozovic, Xi He

We studied structural changes in a 5 unit cell thick La1.96Sr0.04CuO4 film, epitaxially grown on a LaSrAlO4 substrate with a single unit cell buffer layer, when ultra-high electric fields were induced in the film by applying a gate voltage between the film ...

Nature Research2016

Sputtered rear electrode with broadband transparency for perovskite solar cells

Christophe Ballif, Guy Joseph Günter Dubuis, Sylvain Nicolay, Soo-Jin Moon, Arnaud Walter, Stefaan De Wolf, Jérémie Werner, Monica Morales Masis, Björn Niesen, Philipp Friedrich Hermann Löper

Due to their high efficiencies combined with simple and cost-effective device fabrication, perovskite solar cells are promising candidates as top cells in tandem devices. For this application, the perovskite solar cell must be highly transparent at near-in ...

Elsevier2015

Magnetic field, frequency and temperature dependence of complex conductance of ultrathin La1.65Sr0.45CuO4/La2CuO4 films and the organic superconductors kappa-(BEDT-TTF)(2)Cu[N(CN)(2)]Br

Davor Pavuna, Guy Joseph Günter Dubuis, Ivan Bozovic, Xi He

We used atomic-layer molecular beam epitaxy (ALL-MBE) to synthesize bilayer films of a cuprate metal (La1.65Sr0.45CuO4, LSCO) and a cuprate insulator (La2CuO4, LCO), in which interface superconductivity occurs in a layer that is just one-half unit cell thi ...

World Scientific Publ Co Pte Ltd2015

Ionic Liquid Based Field Effect Studies on $La_{2-x}Sr_{x}CuO_{4}$ Films and Related Materials

Guy Joseph Günter Dubuis

EPFL2014

Sub-millikelvin stabilization of a closed cycle cryocooler

Guy Joseph Günter Dubuis, Ivan Bozovic, Xi He

Intrinsic temperature oscillations (with the amplitude up to 1 K) of a closed cycle cryocooler are stabilized by a simple thermal damping system. It employs three different materials with different thermal conductivity and specific heat at various temperat ...

American Institute of Physics2014

On field effect studies and superconductor-insulator transition in high-Tc cuprates

Davor Pavuna, Guy Joseph Günter Dubuis, Ivan Bozovic

We summarize previous field effect studies in high-T (c) cuprates and then discuss our method to smoothly tune the carrier concentration of a cuprate film over a wide range using an applied electric field. We synthesized epitaxial one-unit-cell thick films ...

Springer Berlin Heidelberg2013

Critical Resistance at the Superconductor-Insulator Transition in Hole-Doped Cuprates

Davor Pavuna, Guy Joseph Günter Dubuis, Ivan Bozovic

Here, we show that in several p-type cuprates, the superconductor-to-insulator transition (SIT) occurs at the critical sheet resistance approximately equal to the quantum resistance of pairs, RQ=h/4

e^{2}

=6.5 kΩ. In a relatively broad range of temperature ...

Springer Verlag2013

Atomic-Layer Engineering of Oxide Superconductors

Davor Pavuna, Guy Joseph Günter Dubuis, Ivan Bozovic

Molecular beam epitaxy technique has enabled synthesis of atomically smooth thin films, multilayers, and superlattices of cuprates and other complex oxides. Such heterostructures show high temperature superconductivity and enable novel experiments that pro ...

2012

Electric field effect on superconductivity in $La_{2-x}$$Sr_{x}$$CuO_{4}$

Davor Pavuna, Guy Joseph Günter Dubuis, Ivan Bozovic

We demonstrate a method to tune the carrier concentration of a high temperature superconductor over a wide range, using an applied electric field. Thin film devices were made in an electrical double layer transistor configuration utilizing an ionic liquid. ...

American Institute of Physics2012

Superconductor–insulator transition in La2 − xSrxCuO4 at the pair quantum resistance

Davor Pavuna, Guy Joseph Günter Dubuis, Ivan Bozovic

High-temperature superconductivity in copper oxides arises when a parent insulator compound is doped beyond some critical concentration; what exactly happens at this superconductor–insulator transition is a key open question1. The cleanest approach is to t ...

2011

Impedance measurements of the complex dielectric permittivity of sea ice at 50 MHz: pore microstructure and potential for salinity monitoring

Guy Joseph Günter Dubuis

We report impedance measurements of the complex dielectric permittivity epsilon = epsilon' - j epsilon '' of sea ice and laboratory-grown NaCl single crystals using 50 MHz Stevens Water Monitoring Systems Hydra Probes. Temperature cycling of the single-cry ...

2009