@sineatrix@sciencemastodon.com 100% scientist @BerkeleyLab, 50% artist and 0% arithmetician, asesma.org, đźđȘ (she/her)
Berkeley, CA
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Now that I have a captive audienceâŠ(welcome new followers!) a monster thread on what my paper says, the approximations and the caveats⊠(1/aleph)
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TLDR: My paper did *not* prove nor give evidence of superconductivity in Cu-apatite. It showed interesting structural and electronic properties that have features common with high-Tc superconductors provided Cu is in the right place. Otherwise we get a âboringâ semiconductor.
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What a time to be alive.
âGraph networks trained at scaleâŠdiscover 2.2 million structures⊠many of which escaped previous human chemical intuitionâŠOf these, 381,000 entries live on the updated convex hull as newly discovered materials.â
LFG
nature.com/articles/s41586-0âŠ
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Firstly, itâs so exciting to see the interest in solid-state physics! Welcome to the most exciting subfield of physics ;) And thank you all for the interest!
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The structural distortion and my magnetic calculations of Cu on the Pb(1) also suggest that there might be strong electron-phonon coupling or spin fluctuations in this system (important for the superconducting mechanism)
END OF MEGATHREAD 1
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Gave my promotion talk yesterday. Hereâs a very tired me enjoying the moment after sharing what we have done in the group since it all began in Jan 2019. đŽ
ALT Woman sitting at a table with a glass of champagne
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Flat bands can mean superconductivity, but can also mean a wealth of other phenomena like metal-insulator transitions, charge density waves, magnetism (all interesting!)
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Awesome to see the discussions and explanations of the work, especially those aimed at non-experts. I wish I could keep up and spend more time in these discussions but yâall broke my twitter. My personal fav is that I managed to see is from @MarjBaldwin
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Result 2: The electronic structure of Cu on Pb(1) has isolated flat bands at the Fermi level. These are a direct result of the structural distortion! When I calculate the bands without the distortion, they are not isolated. When I include the distortion, they are!
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Simulation of #LK99 by Sinéad!
Translation for children of the conclusions: if you put the copper impurity in the right place, you may see promising and spooky effects. However in practice it's easy to miss the spot and the impurity ends up elsewhere, where there's no magic.
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Since Cu on Pb(2) is more energetically favorable than Cu on Pb(1) we would expect conventional synthesis methods to favor Cu on Pb(2) over Pb(1). This might make obtaining Cu on Pb(1) more challenging.
The structural distortion and my magnetic calculations of Cu on the Pb(1) also suggest that there might be strong electron-phonon coupling or spin fluctuations in this system (important for the superconducting mechanism)
END OF MEGATHREAD 1
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Looking at the structure, it didnât look like something that would be high-Tc⊠why? A lot of the known high-TC materials are layered, and have substantial amounts of transition metals (e.g. Fe, Cu). This did not. Similar discussions on here including from @sentefmi
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Result 1: Cu on the Pb(1) site causes a volume collapse. This is not especially exciting but was consistent with the experiment. However, what was particularly interesting to me was that the Cu substitution caused the whole crystal structure to collectively distort
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Now, down to it.
Last week when the experimental paper was announced I got plenty of messages....
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We need more women in quantum
Presenting arm-and-longitudinal, a readout strategy based on qubit cloaking. This technique complements the arm-and-release method we introduced last year, together enhancing qubit readout performance for any chi/kappa ratio. Work done with @Manuel_muz.
arxiv.org/abs/2305.00895
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A detail in the paper that was interesting was the predicted volume collapse with Cu â I should be able to see that with the theoretical methods (more on that later) that I use, so I decided to start running the calculations.
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I ran these two sets of calculations (one w/ O, one w/OH). Now that I had the structure, I had to decide which Pb atoms to replace with Cu. (Pink or Purple)
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With the structures, the next was to perform calculations â here I used a standard method called Density Functional Theory (DFT) which uses approximations in practice to solve the quantum mechanics that governs the behavior of ions and electrons in a material.
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Where to start? They had the chemical formula and space group in the paper (what the atoms are, how many there are, and where they go). I found it in the Materials Project. I also looked in a database for experimentally reported crystal structures in a database (ICSD).
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It is extremely effective for a wide range of properties, but has its limitations. For one, the approximations made in the implementation of DFT do not deal with strong âelectron-electronâ interactions well.
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(Cuprates, left and pnictides, right -- known high-TC superconductors). Image from:
sciencedirect.com/science/arâŠ
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(this is a bit weird for this small amount of substitution). I pulled a chemist colleague into my office to ask him if he also thought it was weird. He agreed.
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If Cu is indeed sitting in the Pb(1) site in the apatite structure as they report, then the DFT calculations suggest that there are interesting flat bands that are a result of the structural distortion.
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There are two inequivalent Pb atoms in the structure â I considered both (called Pb(1) and Pb(2)). They report to have Cu on Pb(1) in the exp (pink). Note: this is the opposite to the labeling in the exp paper however I adopted the conventional labeling used in other literature.
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Here I looked at a few reasonable values of U to ensure that I was getting a good match with whatever exp data we had (structure), and that the physics we were focusing on didnât vary much with this parameter.
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One of these is called DFT+U where the U is added to the orbitals that we expect to be treated inadequately. In my case, we expect the d-orbitals in Cu need such a treatment. There are several ways of deciding what value of U should be added (e.g. comparing with experiment).
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Does that mean DFT is rubbish for anything other than the top row of the periodic table? No â we have several ways of augmenting DFT to better include some of these electron-electron interactions.
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You can expect to see these el-el effects as you go further down the periodic table and are pushing more electrons into orbitals.
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Can we as a community stop with the criticism of the grammar and aesthetics of the new high-Tc claim paper and focus on the physics.
Ya I donât like the figures either but itâs a skill I learned from my particular training (US/EU/UK).
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Welcome to the future. âOver 17âdays of continuous operation, the A-Lab realized 41 novel compounds from a set of 58 targets⊠identified using large-scale ab initio phase-stability data from the Materials Project and Google DeepMind.
đ Exciting News! Our A-Lab has revolutionized inorganic materials discovery! Combining ab-initio calculations, historical data from literature, and robotic testing, we're rapidly uncovering new compounds. đ€
nature.com/articles/s41586-0âŠ
Community note
This work may present several non-trivial issues.
nitter.app/Robert_Palgrav
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Postdoc positions available in my group @BerkeleyLab on quantum materials, dark matter and materials for quantum computing! Formal application instructions coming soon be reach out if youâre interested. Youâll be sitting in this building #bestviewfromthelab
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Channeled Ginger Rogers to tell Speaker Pelosi about multiferroics and #materialsproject while walking backwards, in heels.
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We are looking for 2 postdocs to join the team! Projects include theory and calculations of quantum materials, dark matter and oxides. To be considered send your CV with a paragraph on your motivation for joining the group to a sgriffin at lbl dot gov. #bestviewfromthelab
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I got married last week but I still donât have a photo of new hubs and I yet to share with yâall đ. I do, however, have this video clip taken by my new sister in the wee hours at the party and it tells you all you need to know about the day and our family & friends. #renaissance
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Thank goodness last weekâs proposal crunch is over so I can focus on important things
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My Mammy is cutting her trip to visit me in California a little shorter than usual to get #HometoVoteYes. Sheâs on the @AerLingus SFO DUB tonight - say hi if youâre travelling too! Sheâs wearing a pink dress and reading #OMGWACA #Repealthe8h #hometovote
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The Mammy is working on buying up every copy in North County Dublin.
irishtimes.com/news/science/âŠ
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Today was our âwould beâ wedding day but instead we tripped around the California desert art towns and made limoncello from our treeâs lemons. We are fierce lucky all the same.
ALT Woman and man at makeshift bus stop with the estimated time of arrival as âneverâ. Love heart on trailer in the background.
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That's a moiré...
Postdoc position available in my group on theory/calculations of moiré supercrystals. Project in close collaboration with @DKBediako @zuerchlab @UCBerkeley @BerkeleyLab
lbl.referrals.selectminds.coâŠ
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Saw my first dil fridge in the flesh today @BerkeleyLab. Canât wait til these are in everyoneâs phones. #Quantumcomputing
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apatite (noun)
early 19th century: coined in German from Greek apatÄ âdeceitâ (from the mineral's diverse forms and colors).
jstor.org/stable/10.3318/ijeâŠ
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Got to celebrate my PhD advisor @NicolaSpaldin receiving the Hamburg Prize for Theoretical Physics in the amazing setting of @PlanetariumHH @ETH_en @jherzstiftung đđđđŒđ©âđ»
ALT Small stage with Nicola Spaldin and emcee discussing. Large projections in background of Nicola saying âNicola Spaldin is awarded the Hamburg Prize for Theoretical Physics 2022â
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Now make it superconduct
For the first time, Stanford researchers, featuring Prof. Hema Karunadasa, have found a way to create and stabilize an extremely rare form of gold that has lost two negatively charged electrons, denoted Au2+.
Learn more: bit.ly/3txub9q
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A break from regular programming: Today I got news of my first completely clear cervical biopsy in 9 years. Itâs been a journey across countries, gynaes and health insurances (grumble), but some good news! đ„
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New postdoc opening in my group to start ASAP. Working closely with Prof. Sayeef Salahuddin @Berkeley_EECS to develop large-scale models for oxides. More info:
psi-k.net/jobs/postdoc-positâŠ
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Honored to be featured for #DarkMatterDay on my journey to the #darkside feat. @imperialcollege @UCSB_MRSEC @ETH_physics @asesma_news @molecularfndry. Thanks to the wonderful Theresa Duque @BerkeleyLab for the great interview and write up.
Weighing In on âLightâ Dark Matter: Q&A With Staff Scientist SinĂ©ad Griffin:
â⊠the search for #darkmatter is the ultimate materials design challengeâŠâ
- @sineatrix
Q&A: newscenter.lbl.gov/2020/10/3âŠ
@molecularfndry #darkmatterday #womeninSTEM
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We're hiring postdocs in the group!
Details here:
psi-k.net/jobs/postdoc-positâŠ
Posting this as the group have lunch here @molecularfndry #bestviewfromalab
ALT Photo taken from the Molecular Foundry building showing a balcony overlooking green hills and the San Francisco Bay.
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Today a high school mentee absolutely schooled me when Feynman came up in conversation. âYou know he wasnât such a good guy, I think we can find other scientists to look up to.â
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I made a toktik đ
đŠ Our @molecularfndry's @sineatrix is on a quest to find new forms of matter using #quantum mechanics. Learn more about her work in this video made for @CBSUnstoppable for #DarkMatterDay!
âŹïž
@ENERGY's National Labs are Shining a Light on #DarkMatter
energy.gov/articles/does-natâŠ
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There are several details of relative placements of Cu at higher concentrations and on the role of oxygen and hydrogen that would warrant further work!
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Christmas Swim: Pacific Edition. đ„¶đ„¶đ„¶đ„¶đ„¶đ„¶đ„¶đ„¶đ„¶đ„¶đ„¶đ„¶đ„¶đ„¶đ„¶đ„¶đ„¶đ„¶đ„¶đ„¶đ„¶đ„¶đ„¶đ„¶đ„¶đ„¶đ„¶
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Iâm hiring a postdoc to work on using quantum materials for detecting #darkmatter to start this Fall @BerkeleyLab. Some more details in this thread lbl.referrals.selectminds.coâŠ
1/n
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My calculations aren't perfect! Nor are there spherical cows... here are some of the main drawbacks to the assumptions and methods:
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Four sci-generations of physicists @molecularfndry @msd_lbnl (ugrad, grad student, postdoc, PI + two borrowed postdocs) #IamAPhysicist #WomenInSTEM #WomenInScience #InternationalDayOfWomenInScience #griffingroup
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Drawback 3: I assumed that the structure and the Cu placement that the experimentalists report is correct, and that there arenât other defects or effects to consider (e.g. other phases).
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Quantum theory @molecularfndry @BerkeleyLab @APSphysics #apsmarch remote talks recorded! When this PI edits &gets posting approval from the team they will go up on virtualmarchmeeting.com. We all agreed it was just as fun as a regular #apsmarch session but without âCommentâ guy.
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Celebration of the visits of Prof. Amisi Safari (DRC), Prof. Garu Hagoss (@UnivofGh), Prof. Georgies Alene (@AaitOf) as part of @usafri_es @APSphysics w/ hosts Matt Horton, David Prendergast & Jeff Neaton @molecularfndry @BerkeleyLab @BerkeleyPhysics. The end of the beginning!
ALT Photograph of 12 scientists outside a building with balloons in the background
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Drawback 2: As mentioned in the paper and above, DFT does not capture strong correlations. It gives more of a coarse-level understanding of the physics of the system with the true correlated effects requiring theoretical methods other than or in addition to DFT.
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One year, 2.5 proposals, 1.5 papers later, and what we estimate as about 50+ hours on zoom, I finally met @alpsipahigil @BerkeleyLab IRL (totally unplanned by being in the same bar last night) đ»đ§Źđ»
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1. All my DFT calculations are at 0 K â temperature can influence many things including the defect energetics, the favored structure, the electronic structure, etc.
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New hubbie: âyou just turned our wedding into a giant art projectâ
âYes, yes I didâ
âI was elected by the women of Ireland, who instead of rocking the cradle, rocked the systemâ
As usual the legend @sineatrix makes the most beautiful thoughtful presentsđ„°
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If this gets >100 likes @ShellyStem has promised to post a video of her doing an interpretative dance of the paper.
Very excited to announce our paper 'Charged Domain Wall and Polar Vortex Topologies in a Room-Temperature Magnetoelectric #Multiferroic Thin Film' is published @ACS_AMI
@TyndallInstitut @sineatrix @ImpMaterials @BernalNews @PhysicsDeptUL @NicolosiGroup
pubs.acs.org/doi/10.1021/acsâŠ
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Words of wisdom from @molecularfndryâs former director @CarolynBertozzi found on a Materials Science Division @BerkeleyLab whiteboard this morning 1/2
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Chefâs kiss
apatite (noun)
early 19th century: coined in German from Greek apatÄ âdeceitâ (from the mineral's diverse forms and colors).
jstor.org/stable/10.3318/ijeâŠ
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Almost exactly 5 years since she joined as the first postdoc in my group @BerkeleyLab the wonderful Prof. Katie Inzani @UniofNottingham came to visit and finish up some papers (and pick up her #lk99 beanie)
ALT Two women smiling; one wearing a beanie saying lk99
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We're looking for another postdoc to join the team!
psi-k.net/jobs/postdoc-positâŠ
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Woohoo! Congratulations to Samra HusremoviÄ from @DKBediako group for winning the best paper award @molecularfndry @BerkeleyLab user meeting for her latest @acsJACS paper! pubs.acs.org/doi/10.1021/jac⊠(she also gave a fabulous talk if youâre looking for seminar speakers!)
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Donât want to brag but itâs my first year having a 100% record for my January resolution, so hereâs how you can too.
After all of the uncertainty of the last two years; my resolution was simple. I ate ice cream after dinner every night this month. #resolutions
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Gave the â290Kâ seminar @BerkeleyPhysics today which gave me more nerves than normal because it was a return to postdoc home turf... keeping the poster as a reminder (I used to ogle these every week in the elevator to see what cool talks were coming up). Physics out đđ€
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In fact, DFT results can often form the basis of these extra theoretical methods. For instance in a previous paper I used DFT inputs to treat these strong correlations with âDynamical Mean-Field Theoryâ which captures a metal-insulator transition.
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Promotion package submitted in the wee hours today so Iâm going to lie down for a while.
(Flaming June by Frederic Leighton)
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Checking out the Berkeley Library @tcddublin with my former @BerkeleyLab @UCBerkeley buds @tesssmidt + new hubs @audiobridgematt
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Inspired by @zuerchlab we had our first #griffingroup writing retreat today! 9-5 schedule with some structure and best practices but mostly âshut up & writeâ time. 10/10 enjoyed it and want to have it monthly/ every other month, Rethinking how we write papers as a group.
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Come be my colleague and we will rule the nanoscale
An exciting staff scientist opportunity at @molecularfndry @BerkeleyLab: m.rfer.us/LBL33C54V A great opportunity to establish a leading research program with applications to nano/quantum materials, devices, and sensors. Please share with those that might be interested!
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Spend a year in my group at @BerkeleyLab during your PhD â details below & email me if youâre interested (the sooner the better!). Deadline Nov 10.
Attention STEM graduate students! We're now accepting applications for our Graduate Student Research program. It provides awards for outstanding grad students to conduct part of their thesis research at a @ENERGY national laboratory or host site: energy.gov/science/articles/âŠ
ALT U.S. Department of Energy Office of Science Graduate Student Research Program, with photos of three people, two women and one man
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As a scientist in the University of California system I can confirm the minimal disruption. When it does happen that a paper I want is behind the Elsevier wall, I can often find a preprint (go #arxiv), or a few times Iâve emailed authors directly.
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!!! I'm coming to LA !!!
I'm giving the @UCLA physics colloquium on "The Hunt for Cosmic Strings and Dark Matter in Quantum Materials" this Thursday. 4pm in 1-434 Physics and Astronomy building. đŽđ
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Oh hey
"I just loved that you could make a discovery and you are the first person in the world who knows that. That got me hooked on research." - SinĂ©ad Griffin @molecularfndry and @UCBerkeley, talking about her research on materials in @IrishTimes: irishtimes.com/news/science/âŠ
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