1 / 15

Science

2014 Annual Evaluation – Dave Graf – Research Faculty I. Science. Instrumentation. Safety. Outreach. User program service. Science – collaborations :. Cedomir Petrovic and Kefeng Wang (BNL) Published results: SrMnBi 2 CaMnBi 2 LaAgBi 2 Just accepted: Sb 2 Te 2 Se

gaye
Download Presentation

Science

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 2014 Annual Evaluation – Dave Graf – Research Faculty I Science Instrumentation Safety Outreach User program service

  2. Science – collaborations: Cedomir Petrovic and Kefeng Wang (BNL) Published results: SrMnBi2 CaMnBi2 LaAgBi2 Just accepted: Sb2Te2Se Current work: (Pb,Sn)Te NbSb2 FeSb2 XMnBi2 under pressure Tozer Research Group (NHMFL) Depleted Uranium CeIn3 Cr - Fermi surface reconstruction under pressure Ryan Baumbach (NHMFL) Nb2PdS5 under pressure Dissertations defended this year with high P data: Steve Winter – Oakley Group (U. of Waterloo) – FBBO under pressure (submitting changes) SamanGhannadzadeh and Paul Goddard (U. of Oxford) – Spin system (published Rapid w 2nd being prepped) EranManiv (Tel Aviv University) Bi2Se3 - dHvA James Hamlin (UF) and Stan Tozer BiTeI under pressure • Large magnetothermopower and Fermi Surface reconstruction in Sb2Te2Se, K. Wang, D. Graf, C. Petrovic, Physical Review B 89 125202 (2014). • Quasi-two-dimensional Dirac fermions and quantum magnetoresistance in LaAgBi2, K. Wang, D. Graf, C. Petrovic, Physical Review B 87 235101 (2013). • Pressure-driven Fermi surface reconstruction of chromium, R. L. Stillwell, D. Graf, W. A. Coniglio, T. P. Murphy, E. C. Palm, J.-H. Park,….S. W. Tozer, Physical Review B 88 125119 (2013). • Direct measurement of the upper critical field in a cuprate superconductor, G. Grissonnanche,…..N. Doiron-Leyraud and L. Taillefer, Nature Communications 5 3280 (2014). • InfaredVortex-State Electrodynamics in Type-II Superconducting Thin Films, X. Xi, J.-H. Park, D. Graf, G. L. Carr, D. B. Tanner, Physical Review B 87 184503 (2013). • Evolution of magnetic interactions in a pressure-induced Jahn-Teller driven magnetic dimensionality switch, S. Ghannadzadeh, P. A. Goddard,…..S. W. Tozer, D. Graf, and J. A. Schlueter, Physical Review B 87 241102 (2013). • Spin–Charge Coupling in the Molecular Conductor (DIETSe)2FeBr4, M. Maesato,….. D Graf, and J. S. Brooks, Jour. Phys. Soc. Japan (Lett.) 82 043704 (2013). Ali Bangura and Hiro Nakamura (MPI-Stuttgart) STO FETs Huiqiu Yuan, Lin Jiao and Zongfa Weng (Zhejiang University), Eric Bauer (LANL), Stan Tozer (NHMFL) CeRhIn5 under pressure Louis Taillefer and Nicolas Doiron-Leyraud (U. of Sherbrooke) Underdopedcuprates – Exploring CDW order vs hydrostatic pressure Tom Rosenbaum and Sara Haravifard (ANL) Pure and doped 2D model quantum magnet under pressure - SCBO with and without Mg-doping Shanti Deemyad and Anne Marie Schaeffer (U. of Utah) and Tozer Research Group (NHMFL) Lithium

  3. CaMnBi2 and SrMnBi2 • Crossover field for Hall resistance • Pressure dependence of frequency different for Ca, Sr Cedomir Petrovic, Kefeng Wang (BNL) and Stan Tozer (NHMFL) XMnBi2 under pressure

  4. BiTeI – F vs P • Ambient / Low pressures – one frequency • Higher pressures – a second frequency appears James Hamlin (UF) and Stan Tozer BiTeI under pressure

  5. CeRhIn5 under pressure • TDO and Hall measurements in different orientations in the same pressure cell P ~ 1.7 GPa

  6. Instrumentation: • Two-axis rotation • Using the Attocube rotation system to add a “phi” component to rotation • Available LV software is being looked at to potentially allow us to make a user interface for aligning samples in the plane • Hall sensor calibration of System D/E rotators for better accuracy for users • Development of multi-use sample platforms (cantilever / transport / TDO) that Petrovic’s group has used with success • Worked w Jie Wu [Bozovic - BNL] to adapt his sample platforms for use in Cell 9 • Pressure - Two tier system w Tozer design work, material expertise and production with my testing and implementation • Re-visiting Tozer design for TAC to search for a reliable 3.0 GPa cell that we can rotate at 31T • Made small design changes to existing platforms that allowed for a 3.0 GPa RT test

  7. Tozer Acorn Cell [TAC] Goal…reliable pressures of ~ 3.0 GPa within safe constraints

  8. Safety: • Machine shop safety committee • Assisted in reviewing SP-32 – Machine Shop safety • Including the definitions of the “Level I – III” system • Developed a “Level I” machine shop safety course including curriculum, qualification card, and testing. • Delivered this course over four sessions to 8 students for the first class of new MS users since the ISM process was implemented. • Developed SOP checklist for quarter shrinker • This step by step “buddy system” is reviewed and used every year for the Open House and Andy and Eric use it for their own testing • Safety culture sub-committee (DOA?)

  9. Outreach and Mentoring: • NHMFL tours • Open House - Tesla coil and Quarter Shrinker demonstration • Worked with the ES and Sean Coyne to make the tesla coils mobile to clean out the shop and make them available to tour guides • University of Utah - Anne Marie Schaeffer • ~ 1 month visit studying Lithium • University of Oxford – SamanGhannadzadeh • DAC work on • JesseyKrehl and Fernando de Torres – FSU • Thermal measurements for pressure cell modeling • Anna Yannakopolous– FSU • Pressure cell preparation

  10. User program service: • ~ 25 weeks of magnet time supported • Summer School session – Transport techniques for the PPMS • Magnet time reviews for ranking meeting • New DC field website techniques sections: • Contactless conductivity • AC and DC transport • Piezo-dilatometry • Request for Proposal (RFP) update • Collaborative effort w Jon Billings • 28 MW magnet – cryogenic “System F” • EFRC proposal

  11. Science Instrumentation Safety Outreach User program service

  12. Why push for higher pressures? BaFe2As2 - SC found at ~ 2.5 – 3.0 GPa CuF2(H2O)2(pyz) - 2D  1D ordering shift at ~ 0.9 GPa SCBO - Different spin state above ~ 2.0 GPa FBBO - Energy gap closed more than halfway by ~ 2.0 GPa BiTeI - Predicted to have different behavior above 2.0 Gpa CeRhIn5 - Critical pressure ~ 2.1 GPa

  13. Cuprates under pressure • Nov. 2013 – Cell 12 • YBCO 6.54 and 6.67 (12 and 19 kbar – RT) • Nd-LSCO 0.20 and 0.24 (only 19 kbar – RT) • March/April 2014 - Hybrid • YBCO 6.45, 6.67 and 6.51 (20 kbar – RT) • Alternated days between pos and neg polarity for the Hall measurements • Purpose: • Study the FS reconstruction under pressure by Hall effect to check for changes in the pseudogap, FS and CDW

  14. Large amount of science sitting on my HDD that should be published: • EtMe3P[Pd(dmit)2]2 under pressure • (Sr, Ca)MnBi2– pressure dependence of the FS and Hall effect • CeIn3- Hall effect under pressure • (Per)2[Au,Pt](mnt)2

More Related