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Inversion of the Energetic Electron "Zebra Stripe" Pattern Present in the Earth's Inner Belt and Slot Region: First Observations and Interpretation 期刊论文
GEOPHYSICAL RESEARCH LETTERS, 2020, 47 (13)
作者:  Lejosne, Solene;  Mozer, F. S.
收藏  |  浏览/下载:9/0  |  提交时间:2020/06/16
zebra stripe inversion  energetic electrons  inner belt  slot region  electric fields  
Dilatory and Downward Development of 3-m Scale Irregularities in the Funnel-Like Region of a Rapidly Rising Equatorial Plasma Bubble 期刊论文
GEOPHYSICAL RESEARCH LETTERS, 2020, 47 (13)
作者:  Ram, S. Tulasi;  Ajith, K. K.;  Yokoyama, T.;  Yamamoto, M.;  Hozumi, K.;  Shiokawa, K.;  Otsuka, Y.;  Li, G.
收藏  |  浏览/下载:13/0  |  提交时间:2020/06/16
equatorial plasma bubble  ionospheric scintillation  electric fields and model simulations  
Mapping the twist-angle disorder and Landau levels in magic-angle graphene 期刊论文
NATURE, 2020, 581 (7806) : 47-+
作者:  Luck, Katja;  39;Amata, Cassandra
收藏  |  浏览/下载:11/0  |  提交时间:2020/07/03

The recently discovered flat electronic bands and strongly correlated and superconducting phases in magic-angle twisted bilayer graphene (MATBG)(1,2) crucially depend on the interlayer twist angle, theta. Although control of the global theta with a precision of about 0.1 degrees has been demonstrated(1-7), little information is available on the distribution of the local twist angles. Here we use a nanoscale on-tip scanning superconducting quantum interference device (SQUID-on-tip)(8) to obtain tomographic images of the Landau levels in the quantum Hall state(9) and to map the local theta variations in hexagonal boron nitride (hBN)-encapsulated MATBG devices with relative precision better than 0.002 degrees and a spatial resolution of a few moire periods. We find a correlation between the degree of theta disorder and the quality of the MATBG transport characteristics and show that even state-of-the-art devices-which exhibit correlated states, Landau fans and superconductivity-display considerable local variation in theta of up to 0.1 degrees, exhibiting substantial gradients and networks of jumps, and may contain areas with no local MATBG behaviour. We observe that the correlated states in MATBG are particularly fragile with respect to the twist-angle disorder. We also show that the gradients of theta generate large gate-tunable in-plane electric fields, unscreened even in the metallic regions, which profoundly alter the quantum Hall state by forming edge channels in the bulk of the sample and may affect the phase diagram of the correlated and superconducting states. We thus establish the importance of theta disorder as an unconventional type of disorder enabling the use of twist-angle gradients for bandstructure engineering, for realization of correlated phenomena and for gate-tunable built-in planar electric fields for device applications.


SQUID-on-tip tomographic imaging of Landau levels in magic-angle graphene provides nanoscale maps of local twist-angle disorder and shows that its properties are fundamentally different from common types of disorder.


  
Coherent electrical control of a single high-spin nucleus in silicon 期刊论文
NATURE, 2020, 579 (7798) : 205-+
作者:  Dedoussi, Irene C.;  Eastham, Sebastian D.;  Monier, Erwan;  Barrett, Steven R. H.
收藏  |  浏览/下载:10/0  |  提交时间:2020/07/03

Nuclear spins are highly coherent quantum objects. In large ensembles, their control and detection via magnetic resonance is widely exploited, for example, in chemistry, medicine, materials science and mining. Nuclear spins also featured in early proposals for solid-state quantum computers(1) and demonstrations of quantum search(2) and factoring(3) algorithms. Scaling up such concepts requires controlling individual nuclei, which can be detected when coupled to an electron(4-6). However, the need to address the nuclei via oscillating magnetic fields complicates their integration in multi-spin nanoscale devices, because the field cannot be localized or screened. Control via electric fields would resolve this problem, but previous methods(7-9) relied on transducing electric signals into magnetic fields via the electron-nuclear hyperfine interaction, which severely affects nuclear coherence. Here we demonstrate the coherent quantum control of a single Sb-123 (spin-7/2) nucleus using localized electric fields produced within a silicon nanoelectronic device. The method exploits an idea proposed in 1961(10) but not previously realized experimentally with a single nucleus. Our results are quantitatively supported by a microscopic theoretical model that reveals how the purely electrical modulation of the nuclear electric quadrupole interaction results in coherent nuclear spin transitions that are uniquely addressable owing to lattice strain. The spin dephasing time, 0.1 seconds, is orders of magnitude longer than those obtained by methods that require a coupled electron spin to achieve electrical driving. These results show that high-spin quadrupolar nuclei could be deployed as chaotic models, strain sensors and hybrid spin-mechanical quantum systems using all-electrical controls. Integrating electrically controllable nuclei with quantum dots(11,12) could pave the way to scalable, nuclear- and electron-spin-based quantum computers in silicon that operate without the need for oscillating magnetic fields.


  
MMS Observations of Plasma Heating Associated With FTE Growth 期刊论文
GEOPHYSICAL RESEARCH LETTERS, 2019, 46 (22) : 12654-12664
作者:  Akhavan-Tafti, M.;  Slavin, J. A.;  Sun, W. J.;  Le, G.;  Gershman, D. J.
收藏  |  浏览/下载:9/0  |  提交时间:2020/02/17
FTE Growth  Magnetic Reconnection Plasma Heating  Parallel electric fields  Betatron process  Fermi process  
Magnetospheric Multiscale Mission Observations of Reconnecting Electric Fields in the Magnetotail on Kinetic Scales 期刊论文
GEOPHYSICAL RESEARCH LETTERS, 2019
作者:  Macek, W. M.;  Silveira, M. V. D.;  Sibeck, D. G.;  Giles, B. L.;  Burch, J. L.
收藏  |  浏览/下载:16/0  |  提交时间:2019/11/27
reconection  kinetic scales  plasma turbulence  magnetic and electric fields  magnetopause  magnetotail  
Electron-Scale Measurements of Dipolarization Front 期刊论文
GEOPHYSICAL RESEARCH LETTERS, 2018, 45 (10) : 4628-4638
作者:  Liu, C. M.;  Fu, H. S.;  Xu, Y.;  Khotyaintsev, Y. V.;  Burch, J. L.;  Ergun, R. E.;  Gershman, D. G.;  Torbert, R. B.
收藏  |  浏览/下载:8/0  |  提交时间:2019/04/09
electron-scale  dipolarization front  parallel currents  parallel electric fields  energy generation  substorm current wedge  
Energetic Electron Injections Deep Into the Inner Magnetosphere: A Result of the Subauroral Polarization Stream (SAPS) Potential Drop 期刊论文
GEOPHYSICAL RESEARCH LETTERS, 2018, 45 (9) : 3811-3819
作者:  Lejosne, Solene;  Kunduri, B. S. R.;  Mozer, F. S.;  Turner, D. L.
收藏  |  浏览/下载:7/0  |  提交时间:2019/04/09
electric fields  adiabatic invariants  drift paths  SAPS  injections  
Features of Upward Positive Leaders Initiated From Towers in Natural Cloud-to-Ground Lightning Based on Simultaneous High-Speed Videos, Measured Currents, and Electric Fields 期刊论文
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 2017, 122 (23)
作者:  Visacro, Silverio;  Guimaraes, Miguel;  Murta Vale, Maria Helena
收藏  |  浏览/下载:7/0  |  提交时间:2019/04/09
upward positive leader  continuous propagation of positive leader  initiation of upward positive leader  lightning currents and electric fields  high-speed videos of lightning  negative CG lightning  
Spatial Distribution and Properties of 0.1-100 keV Electrons in Jupiter's Polar Auroral Region 期刊论文
GEOPHYSICAL RESEARCH LETTERS, 2017, 44 (18)
作者:  Ebert, R. W.;  Allegrini, F.;  Bagenal, F.;  Bolton, S. J.;  Connerney, J. E. P.;  Clark, G.;  Gladstone, G. R.;  Hue, V.;  Kurth, W. S.;  Levin, S.;  Louarn, P.;  Mauk, B. H.;  McComas, D. J.;  Paranicas, C.;  Reno, M.;  Saur, J.;  Szalay, J. R.;  Thomsen, M. F.;  Valek, P.;  Weidner, S.;  Wilson, R. J.
收藏  |  浏览/下载:13/0  |  提交时间:2019/04/09
Jupiter  polar magnetosphere  polar aurora  electron acceleration  parallel electric fields  Juno