Publications by Richard Gaal | EPFL Graph Search

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We report the temperature dependence of the resistivity and thermoelectric power (TEP) under hydrostatic pressure of the itinerant antiferromagnet BaFe2As2 and the electron-doped superconductor Ba(Fe0.9Co0.1)(2)As-2. We observe a hole-like contribution to the thermopower below the structural/magnetic (S-M) transition in the parent compound that is suppressed in magnitude and temperature with pressure. Pressure increases the contribution of electrons to transport in both the doped and undoped compound. In th

We present the results of a systematic study of the temperature-dependent resistivity and of T-c of a single crystal MgB2 sample as a function of point defect concentration. We have found linear, albeit weak, correlation between the decreasing superconduct ...

We have measured the pressure and temperature dependences of the resistivity and the thermoelectric power of anatase, TiO2. The resistivity varies with T-3 at high temperatures, and its absolute value is in the 1 Omega cm range. Below 60 K, the resistivity ...

We have developed a conducting composite based on multi-walled carbon nanotubes and bisphenol A novolak epoxy resin (SU8) for inkjet printing purposes. We could deposit regular conducting stripes and arrays of 150 mu m spots on glass and on flexible polyet ...

We present a newly-developed microwave probe for performing sensitive high-field/multi-frequency electron spin resonance (ESR) measurements under high hydrostatic pressures. The system consists of a BeCu-made pressure-resistant vessel, which accommodates t ...

We report resistivity and thermo-electric power measurements of the anatase phase of TiO2 under pressure up to 2.3 GPa. Despite its transparent appearance, the single crystal of anatase exhibits a metallic-like resistivity above 60 K, at all pressures. The ...

We report crystal growth at high pressure, structure determination, and magnetic and transport studies of an oxypnictide superconductor Pr4Fe2As2Te1-xO4. Its structure resembles the known 1111 phase except for the considerably larger c lattice constant and ...

The discovery of unconventional superconductivity in a broad class of iron-based materials invoked extensive research on the corresponding compounds of other transition metals. For instance, BaNi2P2 exhibits a superconducting transition with a critical tem ...

The simultaneous application of high magnetic fields and high pressures for controlling magnetic ground states is important for testing our understanding of many-body quantum theory. However, the implementation for neutron scattering experiments presents a ...

We present a combined angle-resolved photoemission spectroscopy and resistivity study of the model Fermi liquid system 1T-TiTe2. From the analysis of the quasiparticle spectral line shape we identify and separately evaluate the electron-electron. electron-phonon, and impurity scattering contributions to the quasiparticle lifetime. There is a clear correspondence between spectroscopic and transport data. A residual low-temperature spectral linewidth (Gamma (o)=17 meV) indicates that the three-dimensional nat

We have extended the range of the high-pressure optical spectroscopy to the far-infrared region keeping the accuracy of ambient-pressure experiments. The developed method offers a powerful tool for the study of pressure-induced phase transitions and electr ...

We report the development of the frequency-modulation (FM) method for measuring electron spin resonance (ESR) absorption in the 210- to 420 GHz frequency range. We demonstrate that using a high-frequency ESR spectrometer without resonating microwave compon ...

The statistical analysis of the length distribution of catalytic chemical vapour deposition synthesized multi-walled carbon nanotubes cut by planetary ball milling is reported. The nanotube lengths follow a log-normal distribution in a broad range of grind ...

The resistivity of a very high quality anatase TiO2 doped with 6% of Nb was measured from 300K down to 40 mK. No sign of superconductivity was detected. Instead, a minute quantity of cation vacancies resulted in a Kondo scattering. Measurements of thermo-e ...

We report the synthesis of Methylammonium Lead Iodide (CH3NH3PbI3) nanowires by a low temperature solution processed crystallization using a simple slip-coating method. The anisotropic particle shape exhibits advantages over nanoparticles in terms of charg ...

We report on the temperature dependence of thermal conductivity of single crystalline and polycrystalline organometallic perovskite CH3NH3PbI3. The comparable absolute values and temperature dependence of the two samples' morphologies indicate the minor ro ...

We report a detailed spectroscopic study of Ti3+ self-doped TiO2 nanowires prepared by high temperature annealing of the protonated titanate nanowires (TiONW) in hydrogen atmosphere. Hydrogenation causes a color change from white to cyan and a major increa ...

Cubic ZnMnO3 powder in the form of well-crystalline nanoflakes have been synthesized at low temperatures from a nitrate precursor. The electrical properties of cubic ZuMnO(3) samples have been established by DC resistivity (rho) and thermo-electric power ( ...

The synthesis and structural and physical properties of iron lanthanide oxypnictide superconductors, L4Fe2As2Te1-xO4 (L = Pr, Sm, Gd), with transition temperature at similar to 25 K are reported. Single crystals have been grown at high pressure using the c ...

The first hybrid phototransistors are reported where the performance of a network of photoactive CH3NH3PbI3 nanowires is enhanced by CVD-grown monolayer graphene. These devices show responsivities as high as ≈2.6 × 106 A W- ...

Richard Gaal

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Pressure effects on the transport coefficients of Ba(Fe_{1−x}Co_{x})_{2}As_{2}

Matthiessen's rule in MgB2: Resistivity and T-c as a function of point defect concentration

Pressure dependence of the large-polaron transport in anatase TiO2 single crystals

Carbon nanotubes-SU8 composite for flexible conductive inkjet printable applications

Continuous-wave far-infrared ESR spectrometer for high-pressure measurements

High-pressure study of anatase TiO2

Pr4Fe2As2Te1-xO4: A layered FeAs-based superconductor

Pressure dependence of superconducting properties of layered BaNi2P2

Bullet pressure-cell design for neutron scattering experiments with horizontal magnetic fields and dilution temperatures

High-resolution angle-resolved photoemission investigation of the quasiparticle scattering processes in a model Fermi liquid: 1T-TiTe2

High-pressure infrared spectroscopy: Tuning of the low-energy excitations in correlated electron systems

Microwave frequency modulation in continuous-wave far-infrared ESR utilizing a quasi-optical reflection bridge

Tuning the length dispersion of multi-walled carbon nanotubes by ball milling

Low temperature resistivity, thermoelectricity, and power factor of Nb doped anatase TiO2

Nanowires of Methylammonium Lead Iodide (CH(3)NH(3)Pbl(3)) Prepared by Low Temperature Solution-Mediated Crystallization

Ultra-Low Thermal Conductivity in Organic-Inorganic Hybrid Perovskite CH3NH3PbI3

Cyan titania nanowires: Spectroscopic study of the origin of the self-doping enhanced photocatalytic activity

Synthesis, electrical resistivity, thermo-electric power and magnetization of cubic ZnMnO3

L4Fe2As2Te1-xO4-yFy (L = Pr, Sm, Gd): A layered oxypnictide superconductor with T-c up to 45 K

Microengineered CH3NH3PbI3 Nanowire/Graphene Phototransistor for Low-Intensity Light Detection at Room Temperature