BEGIN:VCALENDAR VERSION:2.0 PRODID:IEEE vTools.Events//EN CALSCALE:GREGORIAN BEGIN:VTIMEZONE TZID:America/Chicago BEGIN:DAYLIGHT DTSTART:20250309T030000 TZOFFSETFROM:-0600 TZOFFSETTO:-0500 RRULE:FREQ=YEARLY;BYDAY=2SU;BYMONTH=3 TZNAME:CDT END:DAYLIGHT BEGIN:STANDARD DTSTART:20251102T010000 TZOFFSETFROM:-0500 TZOFFSETTO:-0600 RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=11 TZNAME:CST END:STANDARD END:VTIMEZONE BEGIN:VEVENT DTSTAMP:20260325T035834Z UID:AB74192C-4FF3-4434-AD7F-89B2DE92D714 DTSTART;TZID=America/Chicago:20250417T110000 DTEND;TZID=America/Chicago:20250417T120000 DESCRIPTION:Speaker:\n\nBijuan Chen\n\nAffiliation:\n\nHarvard University\n \nTitle:\n\nQuantum Imaging of the Local Diamagnetism and Stress in the Hi gh-Tc Superconductor La₃Ni₂O₇₋δ Under High Pressure\n\nDate/Time: \n\nThursday - April 17\, 2025\n\n11:00 AM\n\nZoom link\n\nhttps://argonne .zoomgov.com/j/1618906752?pwd=M0ajZ7Gfr8crA0MfQNLbByiOvjP5GE.1\n\nAbstract :\n\nHigh-pressure research has been crucial in discovering novel supercon ductors and elucidating the mechanisms behind high-Tc phenomena. The recen t observation of superconductivity in La₃Ni₂O₇₋δ—with an onset near 80 K at pressures above 14 GPa\, exceeding the boiling point of l iquid nitrogen—has sparked significant interest in the superconducting p hases of Ruddlesden-Popper nickelates. Yet\, the intrinsic nature of super conductivity in these materials remains ambiguous due to sample inhomogene ity\, a limited superconducting volume\, and sensitivity to local stress v ariations.\n\nIn this talk\, I will present our research employing quantum imaging to investigate the local superconducting state and stress environ ment in La₃Ni₂O₇₋δ. By embedding nitrogen-vacancy (NV) centers di rectly into a diamond anvil\, we integrate high-resolution optical microsc opy for mapping local magnetic fields and stress with simultaneous in-situ transport measurements. This innovative approach overcomes the averaging limitations of conventional high-pressure magnetometry\, delivering submic ron-scale resolution without extensive background corrections. Our results reveal a strong spatial correlation between the onset of diamagnetism and uniaxial stress\, while regions experiencing significant shear stresses s how a pronounced suppression of superconductivity. These observations enab le us to construct a comprehensive stress–shear–temperature phase diag ram and\, together with energy dispersive X-ray spectroscopy\, demonstrate that superconductivity is confined to regions with the precise La₃Ni₂ O₇₋δ stoichiometry. Ultimately\, our work offers critical insights in to the fundamental nature of superconductivity in this material\, paving t he way for a deeper understanding of the interplay between structure\, str ess\, and superconductivity. Our work marks a substantial step forward in high-pressure physics\, demonstrating the transformative potential of quan tum imaging techniques for local-scale investigations of emergent quantum phenomena.\n\nCo-sponsored by: IEEE Chicago\, IEEE NTC Young Professionals \n\n9700 S Cass Ave\, LEMONT\, Illinois\, United States\, 60439\, Virtual: https://events.vtools.ieee.org/m/481240 LOCATION:9700 S Cass Ave\, LEMONT\, Illinois\, United States\, 60439\, Virt ual: https://events.vtools.ieee.org/m/481240 ORGANIZER:yili@anl.gov SEQUENCE:14 SUMMARY:(Harvard University)Quantum Imaging of High-Tc Superconductor La₃ Ni₂O₇₋δ Under High Pressure URL;VALUE=URI:https://events.vtools.ieee.org/m/481240 X-ALT-DESC:Description: <br /><p><strong data-olk-copy-source="MessageBody" >Speaker:&nbsp\; &nbsp\;</strong></p>\n<p><span class="mark4c6xz1tpb" data -markjs="true" data-ogac="" data-ogab="" data-ogsc="" data-ogsb="">Bijuan< /span>&nbsp\;Chen</p>\n<p>&nbsp\;</p>\n<p><strong>Affiliation:&nbsp\; &nbs p\;</strong></p>\n<p>Harvard University</p>\n<p>&nbsp\;</p>\n<p><strong>Ti tle:&nbsp\;</strong></p>\n<p>Quantum Imaging of the Local Diamagnetism and Stress in the High-Tc Superconductor La₃Ni₂O₇₋&delta\; Under High Pressure</p>\n<p>&nbsp\;&nbsp\;</p>\n<p><strong>Date/Time:&nbsp\; &nbsp\; &nbsp\;</strong></p>\n<p>Thursday - April 17\, 2025</p>\n<p>11:00 AM</p>\ n<p>&nbsp\;</p>\n<p><strong>Zoom link</strong></p>\n<p>https://argonne.zoo mgov.com/j/1618906752?pwd=M0ajZ7Gfr8crA0MfQNLbByiOvjP5GE.1</p>\n<p>&nbsp\; </p>\n<p><strong>Abstract:</strong></p>\n<p>High-pressure research has bee n crucial in discovering novel superconductors and elucidating the mechani sms behind high-Tc phenomena. The recent observation of superconductivity in La₃Ni₂O₇₋&delta\;&mdash\;with an onset near 80 K at pressures above 14 GPa\, exceeding the boiling point of liquid nitrogen&mdash\;ha s sparked significant interest in the superconducting phases of Ruddlesden -Popper nickelates. Yet\, the intrinsic nature of superconductivity in the se materials remains ambiguous due to sample inhomogeneity\, a limited sup erconducting volume\, and sensitivity to local stress variations.</p>\n<p aria-hidden="true">&nbsp\;</p>\n<p>In this talk\, I will present our resea rch employing quantum imaging to investigate the local superconducting sta te and stress environment in La₃Ni₂O₇₋&delta\;. By embedding nitro gen-vacancy (NV) centers directly into a diamond anvil\, we integrate high -resolution optical microscopy for mapping local magnetic fields and stres s with simultaneous in-situ transport measurements. This innovative approa ch overcomes the averaging limitations of conventional high-pressure magne tometry\, delivering submicron-scale resolution without extensive backgrou nd corrections. Our results reveal a strong spatial correlation between th e onset of diamagnetism and uniaxial stress\, while regions experiencing s ignificant shear stresses show a pronounced suppression of superconductivi ty. These observations enable us to construct a comprehensive stress&ndash \;shear&ndash\;temperature phase diagram and\, together with energy disper sive X-ray spectroscopy\, demonstrate that superconductivity is confined t o regions with the precise La₃Ni₂O₇₋&delta\; stoichiometry. Ultima tely\, our work offers critical insights into the fundamental nature of su perconductivity in this material\, paving the way for a deeper understandi ng of the interplay between structure\, stress\, and superconductivity. Ou r work marks a substantial step forward in high-pressure physics\, demonst rating the transformative potential of quantum imaging techniques for loca l-scale investigations of emergent quantum phenomena.</p> END:VEVENT END:VCALENDAR