---
_id: '10620'
abstract:
- lang: eng
text: Partially filled Landau levels host competing electronic orders. For example,
electron solids may prevail close to integer filling of the Landau levels before
giving way to fractional quantum Hall liquids at higher carrier density1,2. Here,
we report the observation of an electron solid with non-collinear spin texture
in monolayer graphene, consistent with solidification of skyrmions3—topological
spin textures characterized by quantized electrical charge4,5. We probe the spin
texture of the solids using a modified Corbino geometry that allows ferromagnetic
magnons to be launched and detected6,7. We find that magnon transport is highly
efficient when one Landau level is filled (ν=1), consistent with quantum Hall
ferromagnetic spin polarization. However, even minimal doping immediately quenches
the magnon signal while leaving the vanishing low-temperature charge conductivity
unchanged. Our results can be understood by the formation of a solid of charged
skyrmions near ν=1, whose non-collinear spin texture leads to rapid magnon decay.
Data near fractional fillings show evidence of several fractional skyrmion solids,
suggesting that graphene hosts a highly tunable landscape of coupled spin and
charge orders.
acknowledgement: We acknowledge discussions with B. Halperin, C. Huang, A. Macdonald
and M. Zalatel. Experimental work at UCSB was supported by the Army Research Office
under awards nos. MURI W911NF-16-1-0361 and W911NF-16-1-0482. K.W. and T.T. acknowledge
support from the Elemental Strategy Initiative conducted by MEXT (Japan) and CREST
(JPMJCR15F3), JST. A.F.Y. acknowledges the support of the David and Lucile Packard
Foundation and and Alfred. P. Sloan Foundation.
article_processing_charge: No
article_type: original
author:
- first_name: H.
full_name: Zhou, H.
last_name: Zhou
- first_name: Hryhoriy
full_name: Polshyn, Hryhoriy
id: edfc7cb1-526e-11ec-b05a-e6ecc27e4e48
last_name: Polshyn
orcid: 0000-0001-8223-8896
- first_name: T.
full_name: Taniguchi, T.
last_name: Taniguchi
- first_name: K.
full_name: Watanabe, K.
last_name: Watanabe
- first_name: A. F.
full_name: Young, A. F.
last_name: Young
citation:
ama: Zhou H, Polshyn H, Taniguchi T, Watanabe K, Young AF. Solids of quantum Hall
skyrmions in graphene. Nature Physics. 2019;16(2):154-158. doi:10.1038/s41567-019-0729-8
apa: Zhou, H., Polshyn, H., Taniguchi, T., Watanabe, K., & Young, A. F. (2019).
Solids of quantum Hall skyrmions in graphene. Nature Physics. Springer
Nature. https://doi.org/10.1038/s41567-019-0729-8
chicago: Zhou, H., Hryhoriy Polshyn, T. Taniguchi, K. Watanabe, and A. F. Young.
“Solids of Quantum Hall Skyrmions in Graphene.” Nature Physics. Springer
Nature, 2019. https://doi.org/10.1038/s41567-019-0729-8.
ieee: H. Zhou, H. Polshyn, T. Taniguchi, K. Watanabe, and A. F. Young, “Solids of
quantum Hall skyrmions in graphene,” Nature Physics, vol. 16, no. 2. Springer
Nature, pp. 154–158, 2019.
ista: Zhou H, Polshyn H, Taniguchi T, Watanabe K, Young AF. 2019. Solids of quantum
Hall skyrmions in graphene. Nature Physics. 16(2), 154–158.
mla: Zhou, H., et al. “Solids of Quantum Hall Skyrmions in Graphene.” Nature
Physics, vol. 16, no. 2, Springer Nature, 2019, pp. 154–58, doi:10.1038/s41567-019-0729-8.
short: H. Zhou, H. Polshyn, T. Taniguchi, K. Watanabe, A.F. Young, Nature Physics
16 (2019) 154–158.
date_created: 2022-01-13T14:45:16Z
date_published: 2019-12-16T00:00:00Z
date_updated: 2022-01-13T15:34:44Z
day: '16'
doi: 10.1038/s41567-019-0729-8
extern: '1'
intvolume: ' 16'
issue: '2'
keyword:
- General Physics and Astronomy
language:
- iso: eng
month: '12'
oa_version: None
page: 154-158
publication: Nature Physics
publication_identifier:
eissn:
- 1745-2481
issn:
- 1745-2473
publication_status: published
publisher: Springer Nature
quality_controlled: '1'
scopus_import: '1'
status: public
title: Solids of quantum Hall skyrmions in graphene
type: journal_article
user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17
volume: 16
year: '2019'
...
---
_id: '10664'
abstract:
- lang: eng
text: "Since the discovery of correlated insulators and superconductivity in magic-angle
twisted bilayer graphene (tBLG) ([1, 2], JCCM April 2018), theorists have been
excitedly pursuing the alluring mix of band topology, symmetry breaking, Mott
insulators and superconductivity at play, as well as the potential relation (if
any) to high-Tc physics. Now a new stream\r\nof experimental work is arriving
which further enriches the story. To briefly recap Episodes 1 and 2 (JCCM April
and November 2018), when two graphene layers are stacked with a small rotational
mismatch θ, the resulting long-wavelength moire pattern leads to a superlattice
potential which reconstructs the low energy band structure. When θ approaches
the “magic-angle” θM ∼ 1 ◦, the band structure features eight nearly-flat bands
which fill when the electron number per moire unit cell, n/n0, lies between −4
< n/n0 < 4. The bands can be counted as 8 = 2 × 2 × 2: for each spin (2×) and
valley (2×) characteristic of monolayergraphene, tBLG has has 2× flat bands which
cross at mini-Dirac points."
article_processing_charge: No
article_type: original
author:
- first_name: Mathew
full_name: Yankowitz, Mathew
last_name: Yankowitz
- first_name: Shaowen
full_name: Chen, Shaowen
last_name: Chen
- first_name: Hryhoriy
full_name: Polshyn, Hryhoriy
id: edfc7cb1-526e-11ec-b05a-e6ecc27e4e48
last_name: Polshyn
orcid: 0000-0001-8223-8896
- first_name: K.
full_name: Watanabe, K.
last_name: Watanabe
- first_name: T.
full_name: Taniguchi, T.
last_name: Taniguchi
- first_name: David
full_name: Graf, David
last_name: Graf
- first_name: Andrea F.
full_name: Young, Andrea F.
last_name: Young
- first_name: Cory R.
full_name: Dean, Cory R.
last_name: Dean
- first_name: Aaron L.
full_name: Sharpe, Aaron L.
last_name: Sharpe
- first_name: E.J.
full_name: Fox, E.J.
last_name: Fox
- first_name: A.W.
full_name: Barnard, A.W.
last_name: Barnard
- first_name: Joe
full_name: Finney, Joe
last_name: Finney
citation:
ama: Yankowitz M, Chen S, Polshyn H, et al. New correlated phenomena in magic-angle
twisted bilayer graphene/s. Journal Club for Condensed Matter Physics.
2019;03. doi:10.36471/jccm_february_2019_03
apa: Yankowitz, M., Chen, S., Polshyn, H., Watanabe, K., Taniguchi, T., Graf, D.,
… Finney, J. (2019). New correlated phenomena in magic-angle twisted bilayer graphene/s.
Journal Club for Condensed Matter Physics. Simons Foundation ; University
of California, Riverside. https://doi.org/10.36471/jccm_february_2019_03
chicago: Yankowitz, Mathew, Shaowen Chen, Hryhoriy Polshyn, K. Watanabe, T. Taniguchi,
David Graf, Andrea F. Young, et al. “New Correlated Phenomena in Magic-Angle Twisted
Bilayer Graphene/S.” Journal Club for Condensed Matter Physics. Simons
Foundation ; University of California, Riverside, 2019. https://doi.org/10.36471/jccm_february_2019_03.
ieee: M. Yankowitz et al., “New correlated phenomena in magic-angle twisted
bilayer graphene/s,” Journal Club for Condensed Matter Physics, vol. 03.
Simons Foundation ; University of California, Riverside, 2019.
ista: Yankowitz M, Chen S, Polshyn H, Watanabe K, Taniguchi T, Graf D, Young AF,
Dean CR, Sharpe AL, Fox EJ, Barnard AW, Finney J. 2019. New correlated phenomena
in magic-angle twisted bilayer graphene/s. Journal Club for Condensed Matter Physics.
03.
mla: Yankowitz, Mathew, et al. “New Correlated Phenomena in Magic-Angle Twisted
Bilayer Graphene/S.” Journal Club for Condensed Matter Physics, vol. 03,
Simons Foundation ; University of California, Riverside, 2019, doi:10.36471/jccm_february_2019_03.
short: M. Yankowitz, S. Chen, H. Polshyn, K. Watanabe, T. Taniguchi, D. Graf, A.F.
Young, C.R. Dean, A.L. Sharpe, E.J. Fox, A.W. Barnard, J. Finney, Journal Club
for Condensed Matter Physics 03 (2019).
date_created: 2022-01-25T15:09:58Z
date_published: 2019-02-28T00:00:00Z
date_updated: 2022-01-25T15:56:39Z
day: '28'
doi: 10.36471/jccm_february_2019_03
intvolume: ' 3'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://www.condmatjclub.org/?p=3541
month: '02'
oa: 1
oa_version: Published Version
publication: Journal Club for Condensed Matter Physics
publication_status: published
publisher: Simons Foundation ; University of California, Riverside
quality_controlled: '1'
status: public
title: New correlated phenomena in magic-angle twisted bilayer graphene/s
type: journal_article
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
volume: '03'
year: '2019'
...
---
_id: '10619'
abstract:
- lang: eng
text: The quantum anomalous Hall (QAH) effect combines topology and magnetism to
produce precisely quantized Hall resistance at zero magnetic field. We report
the observation of a QAH effect in twisted bilayer graphene aligned to hexagonal
boron nitride. The effect is driven by intrinsic strong interactions, which polarize
the electrons into a single spin- and valley-resolved moiré miniband with Chern
number C = 1. In contrast to magnetically doped systems, the measured transport
energy gap is larger than the Curie temperature for magnetic ordering, and quantization
to within 0.1% of the von Klitzing constant persists to temperatures of several
kelvin at zero magnetic field. Electrical currents as small as 1 nanoampere controllably
switch the magnetic order between states of opposite polarization, forming an
electrically rewritable magnetic memory.
acknowledgement: The authors acknowledge discussions with A. Macdonald, Y. Saito,
and M. Zaletel.
article_processing_charge: No
article_type: original
author:
- first_name: M.
full_name: Serlin, M.
last_name: Serlin
- first_name: C. L.
full_name: Tschirhart, C. L.
last_name: Tschirhart
- first_name: Hryhoriy
full_name: Polshyn, Hryhoriy
id: edfc7cb1-526e-11ec-b05a-e6ecc27e4e48
last_name: Polshyn
orcid: 0000-0001-8223-8896
- first_name: Y.
full_name: Zhang, Y.
last_name: Zhang
- first_name: J.
full_name: Zhu, J.
last_name: Zhu
- first_name: K.
full_name: Watanabe, K.
last_name: Watanabe
- first_name: T.
full_name: Taniguchi, T.
last_name: Taniguchi
- first_name: L.
full_name: Balents, L.
last_name: Balents
- first_name: A. F.
full_name: Young, A. F.
last_name: Young
citation:
ama: Serlin M, Tschirhart CL, Polshyn H, et al. Intrinsic quantized anomalous Hall
effect in a moiré heterostructure. Science. 2019;367(6480):900-903. doi:10.1126/science.aay5533
apa: Serlin, M., Tschirhart, C. L., Polshyn, H., Zhang, Y., Zhu, J., Watanabe, K.,
… Young, A. F. (2019). Intrinsic quantized anomalous Hall effect in a moiré heterostructure.
Science. American Association for the Advancement of Science. https://doi.org/10.1126/science.aay5533
chicago: Serlin, M., C. L. Tschirhart, Hryhoriy Polshyn, Y. Zhang, J. Zhu, K. Watanabe,
T. Taniguchi, L. Balents, and A. F. Young. “Intrinsic Quantized Anomalous Hall
Effect in a Moiré Heterostructure.” Science. American Association for the
Advancement of Science, 2019. https://doi.org/10.1126/science.aay5533.
ieee: M. Serlin et al., “Intrinsic quantized anomalous Hall effect in a moiré
heterostructure,” Science, vol. 367, no. 6480. American Association for
the Advancement of Science, pp. 900–903, 2019.
ista: Serlin M, Tschirhart CL, Polshyn H, Zhang Y, Zhu J, Watanabe K, Taniguchi
T, Balents L, Young AF. 2019. Intrinsic quantized anomalous Hall effect in a moiré
heterostructure. Science. 367(6480), 900–903.
mla: Serlin, M., et al. “Intrinsic Quantized Anomalous Hall Effect in a Moiré Heterostructure.”
Science, vol. 367, no. 6480, American Association for the Advancement of
Science, 2019, pp. 900–03, doi:10.1126/science.aay5533.
short: M. Serlin, C.L. Tschirhart, H. Polshyn, Y. Zhang, J. Zhu, K. Watanabe, T.
Taniguchi, L. Balents, A.F. Young, Science 367 (2019) 900–903.
date_created: 2022-01-13T14:21:32Z
date_published: 2019-12-19T00:00:00Z
date_updated: 2023-02-21T16:00:09Z
day: '19'
doi: 10.1126/science.aay5533
extern: '1'
external_id:
arxiv:
- '1907.00261'
pmid:
- '31857492'
intvolume: ' 367'
issue: '6480'
keyword:
- multidisciplinary
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://arxiv.org/abs/1907.00261
month: '12'
oa: 1
oa_version: Preprint
page: 900-903
pmid: 1
publication: Science
publication_identifier:
eissn:
- 1095-9203
issn:
- 0036-8075
publication_status: published
publisher: American Association for the Advancement of Science
quality_controlled: '1'
related_material:
record:
- id: '10697'
relation: other
status: public
- id: '10698'
relation: other
status: public
- id: '10699'
relation: other
status: public
scopus_import: '1'
status: public
title: Intrinsic quantized anomalous Hall effect in a moiré heterostructure
type: journal_article
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
volume: 367
year: '2019'
...
---
_id: '10724'
abstract:
- lang: eng
text: Twisted bilayer graphene (tBLG) near the flat band condition is a versatile
new platform for the study of correlated physics in 2D. Resistive states have
been observed at several commensurate fillings of the flat miniband, along with
superconducting states near half filling. To better understand the electronic
structure of this system, we study electronic transport of graphite gated superconducting
tBLG devices in the normal regime. At high magnetic fields, we observe full lifting
of the spin and valley degeneracy. The transitions in the splitting of this four-fold
degeneracy as a function of carrier density indicate Landau level (LL) crossings,
which tilted field measurements show occur between LLs with different valley polarization.
Similar LL structure measured in two devices, one with twist angle θ=1.08° at
ambient pressure and one at θ=1.27° and 1.33GPa, suggests that the dimensionless
combination of twist angle and interlayer coupling controls the relevant details
of the band structure. In addition, we find that the temperature dependence of
the resistance at B=0 shows linear growth at several hundred Ohm/K in a broad
range of temperatures. We discuss the implications for modeling the scattering
processes in this system.
alternative_title:
- Bulletin of the American Physical Society
article_number: V14.00008
article_processing_charge: No
author:
- first_name: Hryhoriy
full_name: Polshyn, Hryhoriy
id: edfc7cb1-526e-11ec-b05a-e6ecc27e4e48
last_name: Polshyn
orcid: 0000-0001-8223-8896
- first_name: Yuxuan
full_name: Zhang, Yuxuan
last_name: Zhang
- first_name: Matthew
full_name: Yankowitz, Matthew
last_name: Yankowitz
- first_name: Shaowen
full_name: Chen, Shaowen
last_name: Chen
- first_name: Takashi
full_name: Taniguchi, Takashi
last_name: Taniguchi
- first_name: Kenji
full_name: Watanabe, Kenji
last_name: Watanabe
- first_name: David E.
full_name: Graf, David E.
last_name: Graf
- first_name: Cory R.
full_name: Dean, Cory R.
last_name: Dean
- first_name: Andrea
full_name: Young, Andrea
last_name: Young
citation:
ama: 'Polshyn H, Zhang Y, Yankowitz M, et al. Normal state transport in superconducting
twisted bilayer graphene. In: APS March Meeting 2019. Vol 64. American
Physical Society; 2019.'
apa: 'Polshyn, H., Zhang, Y., Yankowitz, M., Chen, S., Taniguchi, T., Watanabe,
K., … Young, A. (2019). Normal state transport in superconducting twisted bilayer
graphene. In APS March Meeting 2019 (Vol. 64). Boston, MA, United States:
American Physical Society.'
chicago: Polshyn, Hryhoriy, Yuxuan Zhang, Matthew Yankowitz, Shaowen Chen, Takashi
Taniguchi, Kenji Watanabe, David E. Graf, Cory R. Dean, and Andrea Young. “Normal
State Transport in Superconducting Twisted Bilayer Graphene.” In APS March
Meeting 2019, Vol. 64. American Physical Society, 2019.
ieee: H. Polshyn et al., “Normal state transport in superconducting twisted
bilayer graphene,” in APS March Meeting 2019, Boston, MA, United States,
2019, vol. 64, no. 2.
ista: 'Polshyn H, Zhang Y, Yankowitz M, Chen S, Taniguchi T, Watanabe K, Graf DE,
Dean CR, Young A. 2019. Normal state transport in superconducting twisted bilayer
graphene. APS March Meeting 2019. APS: American Physical Society, Bulletin of
the American Physical Society, vol. 64, V14.00008.'
mla: Polshyn, Hryhoriy, et al. “Normal State Transport in Superconducting Twisted
Bilayer Graphene.” APS March Meeting 2019, vol. 64, no. 2, V14.00008, American
Physical Society, 2019.
short: H. Polshyn, Y. Zhang, M. Yankowitz, S. Chen, T. Taniguchi, K. Watanabe, D.E.
Graf, C.R. Dean, A. Young, in:, APS March Meeting 2019, American Physical Society,
2019.
conference:
end_date: 2019-03-08
location: Boston, MA, United States
name: 'APS: American Physical Society'
start_date: 2019-03-04
date_created: 2022-02-04T12:25:04Z
date_published: 2019-03-01T00:00:00Z
date_updated: 2022-02-08T10:23:13Z
day: '01'
extern: '1'
intvolume: ' 64'
issue: '2'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://meetings.aps.org/Meeting/MAR19/Session/V14.8
month: '03'
oa: 1
oa_version: Published Version
publication: APS March Meeting 2019
publication_identifier:
issn:
- 0003-0503
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
status: public
title: Normal state transport in superconducting twisted bilayer graphene
type: conference
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
volume: 64
year: '2019'
...
---
_id: '10722'
abstract:
- lang: eng
text: Bilayer graphene, rotationally faulted to ~1.1 degree misalignment, has recently
been shown to host superconducting and resistive states associated with the formation
of a flat electronic band. While numerous theories exist for the origins of both
states, direct validation of these theories remains an outstanding experimental
problem. Here, we focus on the resistive states occurring at commensurate filling
(1/2, 1/4, and 3/4) of the two lowest superlattice bands. We test theoretical
proposals that these states arise due to broken spin—and/or valley—symmetry by
performing direct magnetic imaging with nanoscale SQUID-on-tip microscopy. This
technique provides single-spin resolved magnetometry on sub-100nm length scales.
I will present imaging data from our 4.2K nSOT microscope on graphite-gated twisted
bilayers near the flat band condition and discuss the implications for the physics
of the commensurate resistive states.
alternative_title:
- Bulletin of the American Physical Society
article_number: L14.00006
article_processing_charge: No
author:
- first_name: Marec
full_name: Serlin, Marec
last_name: Serlin
- first_name: Charles
full_name: Tschirhart, Charles
last_name: Tschirhart
- first_name: Hryhoriy
full_name: Polshyn, Hryhoriy
id: edfc7cb1-526e-11ec-b05a-e6ecc27e4e48
last_name: Polshyn
orcid: 0000-0001-8223-8896
- first_name: Jiacheng
full_name: Zhu, Jiacheng
last_name: Zhu
- first_name: Martin E.
full_name: Huber, Martin E.
last_name: Huber
- first_name: Andrea
full_name: Young, Andrea
last_name: Young
citation:
ama: 'Serlin M, Tschirhart C, Polshyn H, Zhu J, Huber ME, Young A. Direct Imaging
of magnetic structure in twisted bilayer graphene with scanning nanoSQUID-On-Tip
microscopy. In: APS March Meeting 2019. Vol 64. American Physical Society;
2019.'
apa: 'Serlin, M., Tschirhart, C., Polshyn, H., Zhu, J., Huber, M. E., & Young,
A. (2019). Direct Imaging of magnetic structure in twisted bilayer graphene with
scanning nanoSQUID-On-Tip microscopy. In APS March Meeting 2019 (Vol. 64).
Boston, MA, United States: American Physical Society.'
chicago: Serlin, Marec, Charles Tschirhart, Hryhoriy Polshyn, Jiacheng Zhu, Martin
E. Huber, and Andrea Young. “Direct Imaging of Magnetic Structure in Twisted Bilayer
Graphene with Scanning NanoSQUID-On-Tip Microscopy.” In APS March Meeting 2019,
Vol. 64. American Physical Society, 2019.
ieee: M. Serlin, C. Tschirhart, H. Polshyn, J. Zhu, M. E. Huber, and A. Young, “Direct
Imaging of magnetic structure in twisted bilayer graphene with scanning nanoSQUID-On-Tip
microscopy,” in APS March Meeting 2019, Boston, MA, United States, 2019,
vol. 64, no. 2.
ista: 'Serlin M, Tschirhart C, Polshyn H, Zhu J, Huber ME, Young A. 2019. Direct
Imaging of magnetic structure in twisted bilayer graphene with scanning nanoSQUID-On-Tip
microscopy. APS March Meeting 2019. APS: American Physical Society, Bulletin of
the American Physical Society, vol. 64, L14.00006.'
mla: Serlin, Marec, et al. “Direct Imaging of Magnetic Structure in Twisted Bilayer
Graphene with Scanning NanoSQUID-On-Tip Microscopy.” APS March Meeting 2019,
vol. 64, no. 2, L14.00006, American Physical Society, 2019.
short: M. Serlin, C. Tschirhart, H. Polshyn, J. Zhu, M.E. Huber, A. Young, in:,
APS March Meeting 2019, American Physical Society, 2019.
conference:
end_date: 2019-03-08
location: Boston, MA, United States
name: 'APS: American Physical Society'
start_date: 2019-03-04
date_created: 2022-02-04T11:54:21Z
date_published: 2019-03-01T00:00:00Z
date_updated: 2022-02-08T10:25:30Z
day: '01'
extern: '1'
intvolume: ' 64'
issue: '2'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://meetings.aps.org/Meeting/MAR19/Session/L14.6
month: '03'
oa: 1
oa_version: Published Version
publication: APS March Meeting 2019
publication_identifier:
issn:
- 0003-0503
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
status: public
title: Direct Imaging of magnetic structure in twisted bilayer graphene with scanning
nanoSQUID-On-Tip microscopy
type: conference
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
volume: 64
year: '2019'
...