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At Yale University...

Detection of a two-phonon mode in a cuprate superconductor via polarimetric resonant inelastic x-ray scattering

Published in Physical Review B on March 18, 2024.

Congratulations to Kirsty and co-authors!

Collaboration spanning Yale University, University of California San Diego, European Synchrotron Radiation Facility, Diamond, Brookhaven National Lab, North Carolina State University, Max Planck Institute – Stuttgart, and the Institut National de la Recherche Scientifique in Canada.

Polarimetric RIXS decomposition of a 2-phonon peak at 140meV.

In this work we report on the detection of a low-intensity Cu-L3 RIXS signal at 140 meV, twice the energy of the bond-stretching (BS) phonon mode, in the cuprate superconductor Bi-2212. Ultrahigh-resolution polarimetric RIXS measurements allow us to resolve the outgoing polarization of the signal and identify this feature as a two-phonon excitation. Often the first approach to resolve subtle RIXS signals is to improve energy resolution. However, decomposition of the scattering processes into different polarimetric channels has the practical effect of separating overlapping signals, making it an important tool in situations where energy resolution cannot be improved. We leveraged this capability, setting a new state-of-the-art standard for polarimetric soft x-ray RIXS measurements.

Interplay of spin and charge order in the electron-doped cuprates

Published in Physical Review B on November 21, 2023.

Congratulations to our collaborators at the University of Wuerzburg and the Karlsruhe Institute of Technology.

Comparison between experiments and theory.

In this work we study magnetic and charge order in electron-doped cuprates starting from a one-band Hubbard model with both on-site and nearest neighbor interactions. This theoretical approach reproduces various features observed by RIXS measurements of NCCO, including incommensurate charge order and paramagnon dispersions.

Electronic stripe patterns near the Fermi level of tetragonal Fe(Se,S)

Published in npj Quantum Materials on October 19, 2023.

Stripe patterns near the Fermi level.

In this work we provide an in-depth investigation of the electronic states of tetragonal FeSe_0.81S_0.19, using scanning tunneling microscopy and spectroscopy (STM/S) measurements, supported by angle-resolved photoemission spectroscopy (ARPES) and theoretical modeling. We find a strong stripe patterns for states near the Fermi level that break rotational symmetry and have different origin than the nematicity in orthorhombic samples.

‘Strange Metal’ sends quantum researchers in circles

Low-energy quasi-circular electron correlations with charge order wavelength in Bi-2212

Article published in Science Advances on July 19, 2023.

(Generative AI image) from YaleNews

In this RIXS work we found evidence for low-energy dynamic charge order correlations along all the directions in the copper-oxide plane by tracking the evolution of the bond stretching phonon.

Also see announcement in Yale News: ‘Strange Metal’ sends quantum researchers in circles

Stabilization of three-dimensional charge order through interplanar orbital hybridization in Pr-YBaCuO_.

Published in Nature Communications on October 19, 2022.

Congratulations to our collaboration team led by Alejandro Ruiz and Alex Frano at UCSD.

In this work we demonstrate that interplanar orbital engineering can be used to surgically control electronic phases in correlated oxides and other layered materials. Specifically in Pr-YBCO a highly correlated 3D charge order state can be stabilized with an out-of-plane correlation length of ~ 364 Å, the largest value for charge order in any cuprate.

A new step in the search for room-temperature superconductors

Enhanced charge density wave coherence in a light-quenched, high-temperature superconductor

Report published in Science on May 19, 2022.

Congratulations to our collaboration team led by Giacomo Coslovich at SLAC!

In this work we found that an infrared pulse can induces a nonthermal response of the charge density wave (CDW) in YBCO, showing a near doubling of the CDW correlation length, caused by the suppression of the superconducting state. The results are consistent with a model where superconductivity plays the dominant role in stabilizing CDW topological defects, such as discommensurations.

Also see announcements in the news: Yale News, SLAC, Science Daily, MirageNews, QMI-UBC, Phys.Org.

Large response of charge stripes to uniaxial stress in ${\mathrm{LNSCO}}^{}{}^{}$

Letter published on April 9, 2021 in Physical Review Research. T.J. Boyle et al. Phys. Rev. Research 3, L022004 – Published 9 April 2021

Congratulations to Tim, Morgan and Alejandro and our collaboration team!

We report resonant x-ray scattering experiments on LNSCO-125 that reveal a significant response of charge stripes to uniaxial tensile stress of $\sim 0.1\mathrm{GPa}$. These effects include a reduction of the onset temperature of stripes by $\sim 50K$, a 29-K reduction of the low-temperature orthorhombic-to-tetragonal transition, competition between charge order and superconductivity, and a preference for stripes to form along the direction of applied stress. Altogether, we observe a dramatic response of the electronic properties of LNSCO-125 to a modest amount of uniaxial stress.

Collaborating groups: da Silva Neto (Yale, Physics and Energy Sciences Institute), Blanco-Canosa (Donostia International Physics Center and IKERBASQUE), Alex Frano (UCSD), BESSY-II at the Helmholtz-Zentrum Berlin, Canadian Light Source, Advanced Light Source, Max-Planck Institute and University of British Columbia (Quantum Matter Institute).

Rethinking the fundamental way electrons interact in quantum materials.

Article published on January 26, 2021 in Nature Communications.

Also see popular articles in the news: YaleNews, QMI-News, UCSD, OperaNews, NewsWise, ScienceSprings …

Published January 2021

Graphical depiction of non-monotonic Coulomb interations between electrons.

In this work we found evidence for dynamic charge order correlations along all the directions in the copper-oxide plane.

Experiments reporting on the orbital symmetries of CDW order in YBCO  (November 2020)

The results of experiments led by David Hawthorn’s group at the University of Waterloo to uncover the orbital symmetries present in copper-oxide plane of YBCO was recently published in Science Advances.

Article Published January 2021

SNOM Lab (October 2020)

Dr. Adrian Gozar leading experiments with the scanning near-field optical microscope (SNOM) with the help of Tim Boyle.

Adrian and SNOM

Tim Boyle

Tim Boyle

Multi-group Journal Club

Various lectures by students, postdocs and professors. A joint effort between our group, UCSD (Alex Frano) and UBC (Fabio Boschini) that started during the covid-19 stay-at-home orders.

Tim (and his cat) lecturing on vortex lattices in superconductors.

Ryan Day (UBC, PhD student) lecturing on the fundamentals of the photoemission process.

Eduardo lecturing on the fundamentals of tunneling.

At UC Davis...

2019

STS experiments on FeSe (September 2019)

Quasiparticle Interference (QPI) measured at the UC Davis STM/S Lab.

Experiments at CLS (September 2019)

We were the first external users to use the QMSC ARPES beam line. Ryan Day (UBC) and Morgan Walker in the photos.

Eventually

it

works !!!

The thrill of bullets !!!

qRIXS at ALS (August 2019)

I went to Berkeley and all I got was this data set! 🙂

Actually the beam line worked beautifully and there is much more coming. Manuscript in preparation, stay tuned!

Paper Published !!! (August 2019)

Study of topological states in Hf₂Te₂P.

Congratulations to Tim and our collaborators in Davis and Berkeley !

Tim’s paper

QPI in Hf2Te2P

Band Structure Mapping from STS. Strong topological state identified (red line is the theoretical prediction).

Temporary Helium Recovery System with a QD ATL80 (July 2019)

Thank you Peter Klavins, Physics Specialist!
Now we can do low temperature STS again 🙂

First Plans

We use the ATL80 in direct recovery. No added noise to the STM system (after a few tricks).

Experiments at BESSY II Synchrotron (May-August 2019)

Collaboration between UC Davis, UCSD (Alex Frano), CIC nanoGUNE (Santiago Blanco-Canosa) and BESSY II (Erinco Schierle and Christian Shussler-Langeheine).

Photo: Morgan Walker (UC Davis), Alejandro Ruiz (UCSD), Tim Boyle (UC Davis)

Photo (left to right): Eduardo, Morgan (UC Davis), Alejandro Ruiz (UCSD), Santi (CIC nanoGUNE) and Alex (UC sand Diego)

Looking at our beloved UE-46

Resonant X-ray Scattering Nostalgia. Users of UE46, is there a better plotting software?

NSF Career awarded for the study of intertwined orders in quantum materials.

See News Articles and Abstract:
https://lettersandscience.ucdavis.edu/blog/two-nsf-career-awards-college-letters-and-science-faculty
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1845994&HistoricalAwards=false

Sloan Research Fellowship in Physics

Awarded to E. H. da Silva Neto, PI (February 2018).

See New Articles and Announcement:
https://sloan.org/fellowships/2019-Fellows
https://www.ucdavis.edu/news/4-receive-sloan-research-fellowships
https://lettersandscience.ucdavis.edu/news/physics-professors-receive-sloan-research-fellowships

2018

Resonant X-ray Scattering Experiments at SLAC

Studying cuprates in collaboration with Prof. Alex Fraño from UC San Diego

Polarimetric RIXS on NCCO published as a Rapid Communication in Physical Review B

We exploited the high-resolution ERIXS spectrometer at the ID32 beamline at the European Synchrotron Radiation Facility to uncover the coupling between dynamic magnetic correlations and charge order in cuprates.

In this collaboration: UC Davis, Max Planck Institute FKF, University of Minnesota, Quantum Matter Institute (UBC), ESRF, CNRS, Karlsruhe Institute for Technology , HZB, AGH Poland.

https://journals.aps.org/prb/abstract/10.1103/PhysRevB.98.161114

(a) 25-K high-energy-resolution (35 meV) spectra taken on the non-SC NCCO, with incoming σ polarization, for two H values, on and off QCO. (b) Energy-momentum structure for the excitations in the non-SC NCCO in the σπ′ channel, which is primarily composed of single spin-flip processes. The color plot in (b) was generated from eight polarization-resolved spectra.

Congratulation to Martin Bluschke and collaborators. (July 2018).

We discovered the 3D stabilization of charge order in YBCO thin films, a behavior similar to what happens in bulk crystals of YBCO in high magnetic fields.

In this collaboration: Max Planck Institute FKF, HZB, UC Davis, UC Berkeley, UC San Diego,  LBNL, IKERBASQUE, Donostia International Physics Center.

https://www.nature.com/articles/s41467-018-05434-8

Panels d–f exhibit reciprocal space maps in the H−L plane, these are produced by subtracting the scattered intensity detected at 300 K from the equivalent map measured at low temperature.

Alex Eisner’s last lecture (June 2018).

Alex Eisner – UC Davis undergraduate class of 2018

Experiments at qRIXS, Advanced Light Source (June 2018)

Tim and the qRIXS spectrometer.

Eduardo and Tim at the qRIXS control

Atoms and QPI on Iron Superconductor (May 2018).

Time-resolved ARPES work lead by Fabio Boschini published! (April 2018)

https://www.nature.com/articles/s41563-018-0045-1

Congratualtions Fabio

Preparing equipment for CLS run (March 2018)

Tim and Sarahi

Unisoku STM Installation (Dec. 2017 – Feb. 2018)

Eduardo and the 7 crates

Receiving the goods with the help from

Unpacking

Putting it together

Eduardo and David Barnes in delight as everyone else works.

First data…

Tim makes his first measurements

2017

Performing Resonant X-ray Scattering experiments at the Canadian Light Source (December 2017).

CLS: Feizhou He, Ronny Sutarto. UC Davis: E.H. da Silva Neto, Davis Unruh and Junhui Shi at the beamline. Photo courtesy of the Canadian Light Source

Davis Unruh – Graduate student

Junhui Shi, Davis Unruh and E.H. da Silva Neto preparing the samples. Photo by the Canadian Light Source.

Feizhou He (CLS) and Tim Boyle (UC Davis) making the final checks of the RXS chamber,

Ultrafast experiments with the free-electron laser at LCLS (November 2017).

E.H. da Silva Neto, Tim Boyle (UC Davis). Giacomo Coslovich (LCLS), Ellia Razzoli and Fabio Boschini (UBC)…

Another night shift with the full team (LCLS + SLAC + UBC + UC Davis)

Performing RIXS experiments at the ESRF (Sep. 2017).