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Search Publications by: Joseph A Stroscio (Fed)

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Displaying 1 - 25 of 88

Visualizing the merger of tunably coupled graphene quantum dots

December 6, 2023
Daniel Walkup, Fereshte Ghahari, Steven R. Blankenship, Kenji Watanabe, Takashi Taniguchi, Nikolai Zhitenev, Joseph A. Stroscio
Coupled quantum dots have been realized in a wide variety of physical systems and have attracted interest for many different applications. Here, we examine novel graphene quantum dots in backgated devices on hBN, and visualize their merger using scanning

A quantum ruler for orbital magnetism in moire quantum matter

October 5, 2023
Marlou Slot, Yulia Maximenko, Paul M. Haney, Sungmin Kim, Daniel Walkup, Evgheni Strelcov, En-Min Shih, Dilek Yildiz, Steven R. Blankenship, Kenji Watanabe, Takashi Taniguchi, Yafis Barlas, Nikolai Zhitenev, Fereshte Ghahari Kermani, Joseph A. Stroscio
Topological properties that underlie the rich emergent phases of moiré quantum matter (MQM) result from the eigenstate geometry of the moiré Hamiltonian. The eigenstate geometry involves the Berry curvature and the less known quantum metric. Most studies

Edge channels of broken-symmetry quantum Hall states in graphene visualized by atomic force microscopy

May 14, 2021
Joseph A. Stroscio, Sungmin Kim, Johannes Schwenk, Daniel T. Walkup, Yihang Zeng, Fereshte Ghahari, Son T. Le, Marlou R. Slot, Julian Berwanger, Steven R. Blankenship, Kenji Watanabe, Takashi Taniguchi, Franz Giessibl, Nikolai Zhitenev, Cory Dean
The quantum Hall (QH) effect, a topologically non-trivial quantum phase, expanded and brought into focus the concept of topological order in physics. The topologically protected quantum Hall edge states are of crucial importance to the QH effect but have

Achieving meV tunneling resolution in an in-operando scanning tunneling microscopy, atomic force microscopy, and magnetotransport system for quantum materials research

July 6, 2020
Johannes Schwenk, Sungmin Kim, Julian Berwanger, Fereshte Ghahari Kermani, Daniel T. Walkup, Marlou R. Slot, Son T. Le, W. G. Cullen, Steven R. Blankenship, Sasa Vranjkovic, Hans Hug, Young Kuk, Franz Giessibl, Joseph A. Stroscio
Research in new quantum materials require multi-mode measurements spanning length scales, correlations of atomic scale variables with macroscopic function, and with an ultimate energy resolution only obtainable at ultra-low temperatures, typically in a

Tuning single-electron charging and interactions between compressible Landau level islands in graphene

January 29, 2020
Daniel T. Walkup, Fereshte Ghahari Kermani, Christopher Guti?rrez, Kenji Watanabe, Takashi Taniguchi, Nikolai B. Zhitenev, Joseph A. Stroscio
Interacting quantum dots (QDs), small chunks of matter with well-separated energies of electronic levels, have been extensively exploited in condensed matter physics and quantum information science. Using a low-temperature scanning tunneling microscope

Interaction-driven quantum Hall wedding cake-like structures in graphene quantum dots

August 24, 2018
Christopher Gutierrez, Daniel T. Walkup, Fereshte Ghahari Kermani, Cyprian Lewandowski, Joaquin R. Nieva, Kenji Watanabe, Takashi Taniguchi, Leonid Levitov, Nikolai Zhitenev, Joseph A. Stroscio
Interactions amongst relativistic particles underpin exotic behaviours in diverse systems ranging from quark-gluon plasmas to Dirac electron fluids in solids. Despite long-standing interest, direct observation of quantum-relativistic matter under ambient

Helical Level Structure of Dirac Potential Wells

November 28, 2017
Daniel T. Walkup, Joseph A. Stroscio
In graphene and other massless 2D Dirac materials, Klein tunneling compromises electron confinement, and momentum-space contours can be assigned a Berry phase which is either zero or π. Consequently, in such systems the energy spectrum of circular

Strain engineering a 4a*?3a charge-density-wave phase in transition-metal dichalcogenide 1T-VSe2

July 19, 2017
Duming Zhang, Jeonghoon Ha, Hongwoo H. Baek, Yang-Hao Chan, Donat F. Natterer, Alline Myers, Joshua D. Schumacher, William Cullen, Albert Davydov, Young Kuk, Mei-Yin Chou, Nikolai Zhitenev, Joseph A. Stroscio
We report a new charge density wave (CDW) structure in strained 1T-VSe2 thin films synthesized by molecular beam epitaxy. The CDW structure is unconventional and exhibits a rectangular 4a×√3a periodicity, as opposed to the previously reported hexagonal 4a

An On/Off Berry Phase Switching with Circular Graphene Resonators

May 26, 2017
Fereshte Ghahari Kermani, Daniel T. Walkup, Christopher Gutierrez, Joaquin R. Nieva, Yue Y. Zhao, Jonathan E. Wyrick, Donat F. Natterer, William G. Cullen, Kenji Watanabe, Takashi Taniguchi, Leonid Levitov, Nikolai B. Zhitenev, Joseph A. Stroscio
Berry phase is an example of anholonomy, where the phase of a quantum state may not return to its original value after its parameters cycle around a closed path; instead the quantum system’s wavefunction may acquire a real measurable phase difference

Interacting nanoscale magnetic cluster arrays in molybdenum oxide bronzes

May 26, 2017
Joseph A. Hagmann, Son T. Le, Lynn F. Schneemeyer, Joseph A. Stroscio, Tiglet Besara, Theo Siegrist, Curt A. Richter, David G. Seiler
In this study, we examine several reduced ternary molybdates in the family of rare earth molybdenum bronzes produced by electrochemical synthesis with composition LnMo16O44. These compounds contain an array of electrically isolated but magnetically

Tomography of a probe potential using atomic sensors on graphene

November 7, 2016
Jonathan E. Wyrick, Donat F. Natterer, Yue Y. Zhao, Kenji Watanabe, Takashi Taniguchi, William G. Cullen, Joseph A. Stroscio
One of the great advances in our ability to probe the quantum world has been the ability to manipulate the electronic structure of materials by constructing artificial nanostructures on surfaces using atomic manipulation of single adatoms with scanning

Energy Bandgap and Edge States in an Epitaxially Grown Graphene/h-BN Heterostructure

August 9, 2016
Beomyong Hwang, Hwang Jeongwoon, Jong K. Yoon, Sungjun Lim, Sungmin Kim, Minjun Lee, Jeong H. Kwon, Hongwoo Baek, Dongchul Sung, Gunn Kim, Suklyun Hong, Jisson Ihm, Joseph A. Stroscio, Young Kuk
Securing a stable bandgap is an essential requirement for applications of graphene layers in switching devices. Theoretical studies have suggested creating a bulk bandgap and modified edge states with an asymmetry between the A and B sub-lattice sites of

Scanning tunneling spectroscopy of proximity superconductivity in epitaxial multilayer graphene

January 7, 2016
Donat F. Natterer, Jeonghoon Ha, Hongwoo H. Baek, Duming Zhang, William G. Cullen, Nikolai B. Zhitenev, Young Kuk, Joseph A. Stroscio
Superconducting aluminum films were grown on multilayer graphene. The aluminum films were discontinuous with networks of trenches in the film morphology reaching down to the substrate to exposed graphene terraces. Superconductivity was induced in

Programmable Extreme Pseudomagnetic Fields in Graphene by a Uniaxial Stretch

December 8, 2015
Shuze Zhu, Joseph A. Stroscio, Teng Li
Many of the properties of graphene are tied to its lattice structure, allowing for tuning of charge carrier dynamics through mechanical strain. The graphene electro-mechanical coupling yields very large pseudomagnetic fields for small strain fields, up to

Creating Nanostructured Superconductors by Local Current Annealing

September 17, 2015
Hongwoo H. Baek, Jeonghoon Ha, Duming Zhang, Bharath NMN Natarajan, Jonathan P. Winterstein, Renu Sharma, Rongwei Hu, Kefeng Wang, Steven Ziemak, Johnpierre Paglione, Young Kuk, Nikolai B. Zhitenev, Joseph A. Stroscio
Superconductivity results from a Bose condensate of Cooper-paired electrons with a macroscopic quantum wavefunction. Dramatic effects can occur when the region of the condensate is shaped and confined to the nanometer scale. Recent progress in

Strong asymmetric charge carrier dependence in inelastic electron tunneling spectroscopy of graphene phonons

June 16, 2015
Donat F. Natterer, Yue Y. Zhao, Jonathan E. Wyrick, Yang-Hao Chan, Wen-Ying Ruan, Mei-Yin Chou, Kenji Watanabe, Takashi Taniguchi, Nikolai B. Zhitenev, Joseph A. Stroscio
The observation of phonons in graphene by inelastic electron tunneling spectroscopy has been met with limited success in previous measurements arising from weak signals and other spectral features which inhibit a clear distinction between phonons and

Creating and Probing Electron Whispering-Gallery Modes in Graphene

May 8, 2015
Yue Y. Zhao, Jonathan E. Wyrick, Donat F. Natterer, Joaquin R. Nieva, Cyprian Lewandowski, Kenji Watanabe, Takashi Taniguchi, Leonid Levitov, Nikolai B. Zhitenev, Joseph A. Stroscio
Designing high-finesse resonant cavities for electronic waves is hampered by the short coherence lengths in solids. Previous approaches, e.g. the seminal nanometer-sized quantum corrals, depend on careful positioning of adatoms at clean surfaces. Here we

Pseudomagnetic Fields in a Locally Strained Graphene Drumhead

August 25, 2014
Shuze Zhu, Yinjun Huang, Nikolai Klimov, David B. Newell, Nikolai Zhitenev, Joseph A. Stroscio, Santiago D. Solares Rivera, Teng Li
Recent experiments reveal that a scanning tunneling microscopy (STM) probe tip can generate a highly localized strain field in a graphene drumhead, which in turn leads to pseudomagnetic fields in the graphene that can spatially confine graphene charge

Quasiparticle scattering from topological crystalline insulator SnTe (001) surface states

June 27, 2014
Duming Zhang, Hongwoo H. Baek, Jeonghoon Ha, Tong Zhang, Jonathan E. Wyrick, Albert Davydov, Young Kuk, Joseph A. Stroscio
Recently, the topological classification of electronic states has been extended to a new class of matter known as topological crystalline insulators. Similar to topological insulators, topological crystalline insulators also have spin-momentum locked

Thermoelectric imaging of structural disorder in epitaxial graphene

July 14, 2013
Sanghee Cho, Stephen D. Kang, Wondong Kim, Eui-Sup Lee, Sung-Jae Woo, Ki-Jeong Kong, Ilyou Kim, Hyeong-Do Kim, Tong Zhang, Joseph A. Stroscio, Yong-Hyun Kim, Ho-Ki Lyeo
Many structural defects and strain fields develop during the preparation of thin films and nanostructures, with their origins being at the atomic level1,2. Sensitively detecting these subtle features with high sensitivity and resolution, and their

Experimental Evidence for s-Wave Pairing Symmetry in Superconducting Cu_x}Bi_2}Se_3} Single Crystals Using a Scanning Tunneling Microscope

March 12, 2013
Niv Levy, Tong Zhang, Jeonghoon Ha, Fred Sharifi, Alec Talin, Young Kuk, Joseph A. Stroscio
Topological superconductors (TS) are a newly predicted phase of matter which is topologically distinct from conventional superconducting condensates of Cooper pairs. As a manifestation of its topological character, TS supports massless itinerant quasi

Scanning Tunneling Microscopy of Gate Tunable Topological Insulator Bi2Se3 Thin Films

March 12, 2013
Tong Zhang, Niv Levy, Jeonghoon Ha, Young Kuk, Joseph A. Stroscio
Electrical field control of the carrier density of topological insulators (TI) has greatly expanded the possible practical use of these materials. However, the combination of low temperature local probe studies and a gate tunable TI device remains

Renormalization of the graphene dispersion velocity determined from scanning tunneling spectroscopy

September 11, 2012
Joseph A. Stroscio, Jungseok Chae, Nikolai B. Zhitenev, Suyong Jung, Andrea F. Young, Cory Dean, Yuanda Gao, Kenji Watanabe, Takashi Taniguchi, James Hone, Kenneth L. Shepard, Philip Kim, Lei Wang
In most metals, electrons behave as non-interacting quasiparticles with renormalized dynamical properties in the presence of electron interactions. Historically, many measurements are capable to probe the effect of interactions at the Fermi energy