Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session C09: DMP Past Chair's Symposium: Tools That Explore Materials PhysicsInvited Session Live Undergrad Friendly
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Sponsoring Units: DMP Chair: Nitin Samarth, Pennsylvania State University; Amanda K Petford-Long, Argonne National Laboratory |
Monday, March 15, 2021 3:00PM - 3:36PM Live |
C09.00001: Combining STM, AFM, and Magnetotransport Measurements for In-Operando Studies of Quantum Materials Invited Speaker: Joseph Stroscio Research in new quantum materials require multi-mode measurements spanning length scales and correlations of atomic scale variables with macroscopic functions. In this talk I describe a multi-mode instrument achieving µeV tunneling resolution with in-operando measurement capabilities of scanning tunneling microscopy (STM), atomic force microscopy (AFM), and magnetotransport inside a dilution refrigerator operating at 10 mK. I illustrate the capabilities of this new instrument in the study of quantum Hall edge states in graphene devices. The edge states, a set of alternating compressible and incompressible strips, are formed at the electrostatic pn junction boundary geometrically defining the Hall bar. To comprehensively characterize these microscopic objects, we apply all capabilities of the new instrument using modalities of AFM, STM, and magnetotransport measurements at mK temperatures. The Kelvin probe force microscopy (KPFM) mode of AFM detects the chemical potential transitions when Landau levels are being filled or emptied as a function of back gate potential. With KPFM we can map the dispersion of the Landau levels across the quantum Hall edge boundary as a function of density and spatial position, including resolving the ν = ±1 edge modes. |
Monday, March 15, 2021 3:36PM - 4:12PM Live |
C09.00002: Capturing In Operando Electronic Structure of Microscopic 2D Materials* Invited Speaker: Eli Rotenberg Angle Resolved Photoemission Spectroscopy (ARPES) is a premier technique for determining the electronic structure of correlated and topological materials. Recently, we and several other groups have adapted ARPES to submicron dimensions through the development of nano-scale scanning X-ray beams, creating so-called nanoARPES endstations at synchrotrons around the world. This exciting technique now enables the in operando measurement of electronic structure for materials in applied fields and currents, as well as the ability to probe the effect of screening and strain on many body physics in confined geometries . In this talk, I will present recent results in which nanoARPES is applied to 2D materials and heterostructures at length scales below 200 nm. These include few layer graphene and transition metal dichalcogenide / graphene heterostructures. Work done in collaboration with Professors T. Heinz (Stanford U.), J. Katoch (CMU), S Ulstrup, J. Miwa, and Ph. Hofmann (Aarhus U.). |
Monday, March 15, 2021 4:12PM - 4:48PM Live |
C09.00003: Ultrafast Electron Calorimetry: Uncovering New Light-Induced Phases in Magnetic and 2D Materials Invited Speaker: Margaret Murnane The ability to probe the full dynamic response of quantum materials on the length- and time-scales (Å to attoseconds on up) fundamental to charge, spin and phonon interactions is leading to a host of new discoveries. Under thermal equilibrium conditions, materials can be tuned by varying the temperature, pressure, chemical doping or dimensionality. Recently, ultrafast light sources have undergone remarkable advances in recent years, achieving what was merely a dream three decades ago, i.e., full coherent control of light fields spanning the THz to the X-ray regions. These new capabilities are providing powerful new tools for coherently manipulating and probing quantum materials using light. We have developed a powerful new method called ultrafast electron calorimetry that can uncover hidden phases in magnetic and charge density wave materials.[1-5] By using time and angle-resolved photoemission spectroscopy to measure the dynamic electron temperature and full band structure as the laser excitation is varied, one can clearly identify when changes in state or couplings occur in a material. This makes it possible to coherently manipulate the structure, electron-phonon couplings, and expand the phase diagram of 2D charge density wave (CDW) materials.[1,3] We can also use light coherently transfer spin polarization from one element to another in a Heusler alloy, on few-femtosecond timescales.[2] |
Monday, March 15, 2021 4:48PM - 5:24PM Live |
C09.00004: Harnessing Nitrogen Vacancy Centers in Diamond for Next-Generation Quantum Science and Technology Invited Speaker: Chunhui Du Advanced quantum systems are integral to both scientific research and modern technology enabling a wide range of emerging applications. Nitrogen vacancy (NV) centers, optically-active atomic defects in diamond, are directly relevant in this context due to their single-spin sensitivity and functionality over a broad temperature range. Many of these advantages derive from their quantum-mechanical nature of NV centers that are endowed by excellent quantum coherence, controllable entanglement, and high fidelity of operations, enabling opportunities to outperform their classical counterpart. In this talk, I will present our recent efforts in developing NV-based quantum sensing platform and technologies. Specifically, we demonstrated electrical control of the coherent spin rotation rate of a single-spin qubit in an NV-spintronic hybrid quantum system. By utilizing electrically generated spin currents, we are able to achieve efficient tuning of magnetic damping and the amplitude of the dipolar fields generated by a micrometer-sized resonant magnet, enabling electrical control of the Rabi oscillation frequency of NV spin qubits. In addition, exploiting a state-of-the-art NV quantum sensing platform, we achieved optical detection of magnons with a broad range of wavevectors in magnetic insulator thin films. Our results highlight the potential of NV centers in designing functional hybrid solid-state systems for next-generation quantum-information technologies. The demonstrated coupling between NV centers and magnons further points to the possibility to establish macroscale entanglement between distant spin qubits and paves the way for developing transformative NV-based quantum computer. |
Monday, March 15, 2021 5:24PM - 6:00PM Live |
C09.00005: Honey, I Shrunk the Synchrotron: Electron Microscopy in Condensed Matter Physics Invited Speaker: Juan Idrobo The new generation of monochromated aberration-corrected scanning transmission electron microscopes (MAC-STEMs) are now capable of rival the capabilities of synchrotrons and in many cases supersede them. The later is evident when exploring local emerging phenomena in materials with high spatial resolutions. |
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