A5023237087- Organic and Molecular Conductors Research
- Physics of Superconductivity and Magnetism
- Iron-based superconductors research
- Rare-earth and actinide compounds
- Advanced Chemical Physics Studies
- Magnetic and transport properties of perovskites and related materials
- Spectroscopy and Quantum Chemical Studies
- Solid-state spectroscopy and crystallography
- Quantum and electron transport phenomena
- Laser-Matter Interactions and Applications
- Magnetic Properties and Applications
- Magnetic Properties of Alloys
- Topological Materials and Phenomena
- Phase-change materials and chalcogenides
- Cold Atom Physics and Bose-Einstein Condensates
- Inorganic Chemistry and Materials
- Superconducting Materials and Applications
- Advanced Condensed Matter Physics
- Advanced Thermodynamics and Statistical Mechanics
- Machine Learning in Materials Science
- High-pressure geophysics and materials
- Photorefractive and Nonlinear Optics
- scientometrics and bibliometrics research
- Molecular Junctions and Nanostructures
- Electronic and Structural Properties of Oxides
Stanford University
2018-2024
École Polytechnique Fédérale de Lausanne
2021-2024
SLAC National Accelerator Laboratory
2018-2023
Menlo School
2018-2022
Scottish Universities Physics Alliance
2022
University of St Andrews
2022
Max Planck Institute for Chemical Physics of Solids
2022
Stanford Medicine
2020
Iowa State University
2014
RWTH Aachen University
2014
Complex systems, which consist of a large number interacting constituents, often exhibit universal behavior near phase transition. A slowdown certain dynamical observables is one such recurring feature found in vast array contexts. This phenomenon, known as critical slowing-down, well studied mostly thermodynamic transitions. However, it less understood highly nonequilibrium settings, where the time takes to traverse boundary becomes comparable timescale fluctuations. Using transient optical...
Abstract The Bragg glass phase is a nearly perfect crystal with glassy features predicted to occur in vortex lattices and charge-density-wave systems the presence of disorder. Detecting it has been challenging, despite its sharp theoretical definition terms diverging correlation lengths. Here we present bulk probe evidence supporting systematically disordered material Pd x ErTe 3 . We do this by using comprehensive X-ray data machine-learning-based analysis tool called diffraction...
The momentum dependence of the nematic order parameter is an important ingredient in microscopic description iron-based high-temperature superconductors. While recent reports on FeSe indicate that changes sign between electron and hole bands, detailed knowledge still missing for other compounds. Combining angle-resolved photoemission spectroscopy with uniaxial strain tuning, we measure band splitting both ${\mathrm{BaFe}}_{2}{\mathrm{As}}_{2}$ without interference from either twinning or...
Quantum criticality has been invoked as being essential to the understanding of a wide range exotic electronic behavior, including heavy Fermion and unconventional superconductivity, but conclusive evidence quantum critical fluctuations elusive in many materials current interest. An expected characteristic feature is power law behavior thermodynamic quantities function non-thermal tuning parameter close point (QCP). In present work, we observe temperature coupled nematic/structural phase...
We report the separate response of critical temperature nematic phase transition $T_{\rm S}$ to symmetric and antisymmetric strains for prototypical underdoped iron pnictide Ba(Fe$_{0.975}$Co$_{0.025}$)$_2$As$_2$. This decomposition is achieved by comparing uniaxial stress hydrostatic pressure. In addition quantifying two distinct linear responses strains, we find a quadratic variation as $\epsilon_{\rm B_{1g}}$=$\frac{1}{2}$($\epsilon_{\rm xx}$-$\epsilon_{\rm yy}$), exceeding non at least...
Pd-intercalated ErTe3 is studied as a model system for the interplay between bidirectional two component charge density wave (CDW) state and disorder. Using scanning tunneling microscopy (STM), we show that introducing Pd-intercalants (i.e. disorder) disrupts long-range order of both CDW states via creation dislocations, which appear associated with each separately. While weak disorder continue to coexist throughout sample, no "domains" one direction or another, increasing Pd concentration...
We report the evolution of charge density wave (CDW) states in quasi-two-dimensional rare-earth tritellurides (RTe3 for R=Er, Tm) under influence in-plane uniaxial stress. Measurements elastocaloric effect, resistivity, and elastoresistivity allow us to demonstrate importance antisymmetric strain on CDW establish a phase diagram. show that modest tensile stress parallel axis can reversibly switch direction ordering vector between two directions, present free-energy expansion which reproduces...
Adiabatic decompression of paraquadrupolar materials has significant potential as a cryogenic cooling technology. We focus on TmVO <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:msub> <mml:mrow/> <mml:mn>4</mml:mn> </mml:msub> </mml:math> , an archetypal material that undergoes continuous phase transition to ferroquadrupole-ordered state at 2.15 K. Above the transition, each Tm ion contributes entropy <mml:mrow> <mml:mi>k</mml:mi>...
Electrochemical metallisation (ECM) memory cells potentially suffer from limited retention time, which slows down the future commercialisation of this type data memory. In work, we investigate Ag/GeSx/Pt redox-based resistive (ReRAM) with and without an additional Ta barrier layer by time-of-flight secondary ion mass spectrometry (ToF-SIMS), X-ray absorption spectroscopy (XAS) synchrotron high-energy diffractometry (XRD) to physical mechanism behind shift and/or loss OFF retention....
Disorder is generically anticipated to suppress long range charge density wave (CDW) order. We report transport, thermodynamic, and scattering experiments on ${\mathrm{Pd}}_{x}{\mathrm{ErTe}}_{3}$, a model CDW system with disorder induced by intercalation. The pristine parent compound ($x=0$) shows two separate, mutually perpendicular, incommensurate unidirectional phases setting in at 270 K 165 K. In this work we present measurements finely-spaced series of single crystal samples, which...
Engineering novel states of matter with light is at the forefront materials research. An intensely studied direction to realize broken-symmetry phases that are "hidden" under equilibrium conditions but can be unleashed by an ultrashort laser pulse. Despite a plethora experimental discoveries, nature these orders and how they transiently appear remain unclear. To this end, we investigate nonequilibrium charge density wave (CDW) in rare-earth tritellurides, which suppressed emerges after...
Abstract The so-called “extreme magnetoresistance” (XMR) found in few conductors poses interesting conceptual challenges which address needs technology. In contrast to the more common XMR semi-metals, PtSn 4 stands out as a rare example of high carrier density multi-band metal exhibiting XMR, sparking an active debate about its microscopic origin. Here we report sharp sensitivity upon field angle, with almost complete collapse only for one specific current and direction (B// b , I// )....
Elastoresistivity, the relation between resistivity and strain, can elucidate subtle properties of electronic structure a material is an increasingly important tool for study strongly correlated materials. To date, elastoresistivity measurements have predominantly been performed with quasi-static (DC) strain. In this work, we demonstrate method using AC strain in measurements. A sample experiencing has time-dependent resistivity, which modulates voltage produced by current; effect produces...
The authors explore the $R$Te${}_{3}$ family of materials as a clean model system in which to study quantum phase transition between single and double charge density wave states. Quantum oscillation measurements reveal significant reduction area Fermi surface across transition, but no obvious divergence electronic effective mass. Variation magnitude gap rare-earth series leads particularly clear example tunable magnetic breakdown.
Performing time and angle resolved photoemission spectroscopy (tr-ARPES) at high momenta necessitates extreme ultraviolet laser pulses, which are typically produced via harmonic generation (HHG). Despite recent advances, HHG-based setups still require large pulse energies (hundreds of $\mu$J to mJ) their energy resolution is limited tens meV. Here, we present a novel 11 eV tr-ARPES setup that generates flux $5\times10^{10}$ photons/s achieves an unprecedented 16 It can be operated repetition...
The authors combine data from Scanning Tunneling Spectroscopy, resistivity, and ac susceptibility to explore the relation between charge density waves superconducting orders in Pd-intercalated ErTe${}_{3}$.
Studying the response of materials to strain can elucidate subtle properties electronic structure in strongly correlated materials. Here, we focus on elastocaloric coefficients, forming a second rank tensor quantity describing relation between entropy and strain. In contrast better-known elastoresistivity, effect is thermodynamic quantity. Experimentally, measurements are demanding since conditions during measurement have be well controlled. this work, present technique measure under...
A uniform superfluid response in superconducting quasi-2D Pd-intercalated ErTe${}_{3}$ was observed using scanning SQUID susceptometry, which suggests quantum phase fluctuations that may suppress ${T}_{c}$.
Strong electronic nematic fluctuations have been discovered near optimal doping for several families of Fe-based superconductors, motivating the search a possible link between these fluctuations, quantum criticality, and high temperature superconductivity. Here we probe key prediction namely power law dependence associated susceptibility as function composition approaching compositionally-tuned putative critical point. To 'bare' point requires suppression superconducting state, which achieve...
In the iron-based superconductors, both nematic and magnetic fluctuations are expected to enhance superconductivity may originate from a quantum critical point hidden beneath superconducting dome. The behavior of non-superconducting state can be an important piece puzzle, motivating in this paper use high fields suppress measure susceptibility normal at low temperatures. We describe experimental advances which make it possible resistive gauge factor (which is proxy for susceptibility)...
We present a comprehensive study of the frequency-dependent sensitivity for measurements AC elastocaloric effect by applying both exactly soluble models and numerical methods to oscillating heat flow problem. These reproduce finer details thermal transfer functions observed in experiments, considering here representative data single-crystal Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$. Based on our results, we propose set practical guidelines experimentalists using this technique. This work establishes...