A5089395057- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Physics of Superconductivity and Magnetism
- Iron-based superconductors research
- Magnetic and transport properties of perovskites and related materials
- Advanced Condensed Matter Physics
- Graphene research and applications
- Rare-earth and actinide compounds
- Topological Materials and Phenomena
- 2D Materials and Applications
- Inorganic Chemistry and Materials
- Terahertz technology and applications
- Organic and Molecular Conductors Research
- Metamaterials and Metasurfaces Applications
- Electronic and Structural Properties of Oxides
- Photonic and Optical Devices
- Fiber-reinforced polymer composites
- Plasmonic and Surface Plasmon Research
- Heusler alloys: electronic and magnetic properties
- Thermal Expansion and Ionic Conductivity
- Perovskite Materials and Applications
- Multiferroics and related materials
- Superconductivity in MgB2 and Alloys
- Diamond and Carbon-based Materials Research
- Carbon Nanotubes in Composites
Loughborough University
2013-2024
Technical University of Munich
2017
University of Edinburgh
2009-2013
University of Cambridge
2006-2011
Institut de Ciència de Materials de Barcelona
2010
École Polytechnique Fédérale de Lausanne
2008-2009
The interplay between superconductivity and the charge-density wave (CDW) state in pure 1T-TiSe(2) is examined through a high-pressure study extending up to pressures of 10 GPa sub-Kelvin room temperatures. At critical pressure 2 superconducting phase sets persists 4 GPa. maximum transition temperature 1.8 K. These findings complement recent discovery copper-intercalated 1T-TiSe(2). comparisons normal properties two systems reveal possibility that emergent electronic qualitatively depends on...
A remarkable electronic flexibility and colossal magnetoresistance effects have been discovered in the perovskite oxynitrides EuWO1+xN2−x. Ammonolysis of Eu2W2O9 yields scheelite-type intermediates EuWO4−yNy with a very small degree nitride substitution (y = 0.04) then EuWO1+xN2−x perovskites that show wide range compositions −0.16 ≤ x 0.46. The cubic lattice parameter varies linearly x, but electron microscopy reveals tetragonal superstructure. previously unobserved < 0 regime corresponds...
Incommensurate Mn spin order has been discovered in the perovskite MnVO${}_{3}$ containing localized 3d${}^{5}$ Mn${}^{2+}$ and itinerant 3d${}^{1}$ V${}^{4+}$ states. This phase a distorted Pnma crystal structure (a = 5.2741(6) \AA{}, b 7.4100(11) c 5.1184(8) \AA{} at 300 K) is metallic temperatures of 2--300 K pressures up to 67 kbar. Neutron scattering reveals (0.29 0 0) magnetic vector below 46 ordering transition, both helical density wave orderings are consistent with diffraction...
Weyl semimetals are materials with topological defects in their band structure. They arise through mechanisms similar to vortex--anti-vortex pair creation, forming a hedgehog-structure momentum space that is described by four-dimensional energy-momentum Dirac cone. The authors show that, under pressure, the cone can be tilted same way as relativistic light on approach black hole horizon. Following this analogy, at defined horizon, time and reversal may trigger unconventional phenomena,...
Abstract The discovery of twisted bilayer graphene with tunable superconductivity has diverted great focus at the world van der Waals heterostructures. Here we propose a paradigm for materials, where covalent bonding replaces interaction between layers. On example germanene-stanene bilayer, show that such systems demonstrate fascinating topological properties and manifest giant capacitance effects order C = 10 2 μ F as well dipole-like charge densities q 1 − × −4 cm −2 , showing promise 2D...
The structural and magnetic properties of deuterated herbertsmithite have been studied by means neutron powder diffraction susceptibility measurements in a wide range temperatures pressures. experimental data demonstrate that phase transition from the quantum-disordered spin-liquid to long-range ordered antiferromagnetic with N\'eel temperature ${T}_{N}=6\text{ }\text{ }\mathrm{K}$ is induced at $P=2.5\text{ }\mathrm{GPa}$. observed decrease ${T}_{N}$ upon compression correlates anomalies...
The crystal structures of bis(3-fluoro-salicylaldoximato)nickel(II) and bis(3-methoxy-salicylaldoximato)nickel(II) have been determined at room temperature between ambient pressure approximately 6 GPa. principal effect is to reduce intermolecular contact distances. In the fluoro system molecules are stacked, Ni⋅⋅⋅Ni distance decreases from 3.19 Å 2.82 5.4 These data similar those observed in bis(dimethylglyoximato)nickel(II) over a range, though contrary that system, spite their structural...
We have studied the evolution, with hydrostatic pressure, of recently-discovered superconductivity in graphite intercalation compounds ${\mathrm{C}}_{6}\mathrm{Yb}$ and ${\mathrm{C}}_{6}\mathrm{Ca}$. present pressure-temperature phase diagrams, for both superconductors, established by electrical transport magnetization measurements. In range $0--1.2\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ superconducting transition temperature increases linearly pressure materials...
The magnetic field and voltage dependent electronic transport properties of EuWO1+xN2−x ceramics are reported. Large negative magnetoresistances observed at low temperatures, up to 70% in the least doped (x=0.09) material. Non-Ohmic conduction emerges below 12 K Curie transition. This is attributed a microstructure ferromagnetic conducting antiferromagnetic insulating regions resulting from small spatial fluctuations chemical doping.
A suppression of superconductivity in the late rare-earth $R{\text{FeAsO}}_{1\ensuremath{-}x}{\text{F}}_{x}$ materials is reported. The maximum critical temperature $({T}_{c})$ decreases from 51 K for $R=\text{Tb}$ to 36 ${\text{HoFeAsO}}_{0.9}{\text{F}}_{0.1}$, which has been synthesized under 10 GPa pressure. This driven by a decrease Fe-As-Fe angle below an optimum value $110.6\ifmmode^\circ\else\textdegree\fi{}$, as linearly with unit-cell volume $(V)$ across series. crossover electronic...
We report the discovery of remarkable photo-physical phenomena with characteristics unique to epitaxial graphene grown on 6H-SiC (000-1). Surprisingly, electrical resistance increases under light illumination in contrast conventional materials where it normally decreases. The shows logarithmic temperature dependences which may be attributed an Altshuler-Aronov effect. show that photoresistance depends frequency irradiating light, three lasers (red, green, and violet) used demonstrate...
A nanocomposite with a unique satellite dish-like structure, termed arsenic (III) oxide iodide (AsO2I)/polypyrrole (Ppy) intercalated ions (AsO2I/Ppy-I), has been meticulously developed via two-step process. It features natural nanostructures, potentially serving as nanoresonators for efficient single photon absorption. With bandgap of 2.8 eV, the AsO2I/Ppy-I efficiently absorbs photons in UV and visible light regions, making it suitable detection. Impressive performance is seen photocurrent...
This paper presents the results of a high pressure study on ferrimagnetic compound ErCo2, which exhibits at ambient magnetic ordering below TC = 33 K, where localized Er moments order ferromagnetically, and itinerant in Co sublattice, align antiparallel to moments. In paramagnetic range, clustering is observed Tf ∼ 100 K for term “parimagnetism” has been proposed. contrast pronounced peak AC susceptibility data only tiny “bump” shows up Tf. The decrease both with applied hydrostatic...
High-field electrical transport and point-contact tunneling spectroscopy were used to investigate superconducting properties of the unique spinel oxide, LiTi$_2$O$_{4-\delta}$ films with various oxygen content. We find that upper critical field $B_\mathrm{c2}$ gradually increases as more impurities are brought into samples by carefully tuning deposition atmosphere. It is striking although transition temperature energy gap almost unchanged, an astonishing isotropic up $\sim$ 26 Tesla observed...
The orbital ordering transition in the metallic perovskite PbRuO${}_{3}$ is suppressed from 90 K at ambient pressure towards zero temperature 50 kbar, where non-Fermi liquid resistivity with a exponent $n$ $=$ 1.6 observed. This evidences possible quantum critical point brought about by fluctuations, rather than spin fluctuations as observed Sr${}_{3}$Ru${}_{2}$O${}_{7}$ and heavy fermion conductors. An anomalous increase of pressures above \ensuremath{\sim}100 to more resistive, possibly...
The terahertz (THz) frequency range is incredibly important as it covers electromagnetic emissions typical for biological and molecular processes. All molecules emit THz waves in a unique fingerprint pattern, although the intensity of such signals usually too weak to be detected. To address efficiency gap existing devices extremely create surfaces with perfect anti-reflection properties. Although metals are absolutely reflective, here we show both theoretically experimentally that by...
Localisation phenomena in highly disordered metals close to the extreme conditions determined by Mott-Ioffe-Regel (MIR) limit when electron mean free path is approximately equal interatomic distance a challenging problem. Here, shed light on these localisation phenomena, we studied dc transport and optical conductivity properties of nanoscaled multilayered films composed metallic Ta magnetic FeNi nanoisland layers, where ferromagnetic nanoislands have giant moments 10[Formula: see...
Resistivity and powder X-ray diffraction measurements on Cs(2)Au(2)I(6) up to 320 kbar pressure show that the suppression of Au(+)/Au(3+) charge order above 55 results in a non-metallic phase containing localised Au(2+) states is irreversibly amorphised 120 kbar, gradual metallisation observed 175 may result from decomposition within amorphous material.
The associations between emergent physical phenomena (e.g., superconductivity) and orbital, charge, spin degrees of freedom $3d$ electrons are intriguing in transition metal compounds. Here, we successfully manipulate the superconductivity spinel oxide ${\mathrm{Li}}_{1\ifmmode\pm\else\textpm\fi{}x}{\mathrm{Ti}}_{2}{\mathrm{O}}_{4\ensuremath{-}\ensuremath{\delta}}$ (LTO) by ionic liquid gating. A dome-shaped superconducting phase diagram is established, where two insulating phases disclosed...
We present an overview of unconventional metallic states arising close to magnetic quantum critical points with a focus on d-electron systems. The applicability and potential breakdowns traditional self-consistent field theories such materials are discussed as well related phenomena in other