---
_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'
...
---
_id: '10725'
abstract:
- lang: eng
text: Bilayer graphene with ~ 1.1 degrees twist mismatch between the layers hosts
a low energy flat band in which the Coulomb interaction is large relative to the
bandwidth, promoting correlated insulating states at half band filling, and superconducting
(SC) phases with dome-like structure neighboring correlated insulating states.
Here we show measurements of a dual-graphite-gated twisted bilayer graphene device,
which minimizes charge inhomogeneity. We observe new correlated phases, including
for the first time a SC pocket near half-filling of the electron-doped band and
resistive states at quarter-filling of both bands that emerge in a magnetic field.
Changing the layer polarization with vertical electric field reveals an unexpected
competition between SC and correlated insulator phases, which we interpret to
result from differences in disorder of each graphene layer and underscores the
spatial inhomogeneity like twist angle as a significant source of disorder in
these devices [1].
alternative_title:
- Bulletin of the American Physical Society
article_number: R14.00004
article_processing_charge: No
author:
- first_name: Shaowen
full_name: Chen, Shaowen
last_name: Chen
- first_name: Matthew
full_name: Yankowitz, Matthew
last_name: Yankowitz
- first_name: Hryhoriy
full_name: Polshyn, Hryhoriy
id: edfc7cb1-526e-11ec-b05a-e6ecc27e4e48
last_name: Polshyn
orcid: 0000-0001-8223-8896
- first_name: Kenji
full_name: Watanabe, Kenji
last_name: Watanabe
- first_name: Takashi
full_name: Taniguchi, Takashi
last_name: Taniguchi
- first_name: David E.
full_name: Graf, David E.
last_name: Graf
- first_name: Andrea
full_name: Young, Andrea
last_name: Young
- first_name: Cory R.
full_name: Dean, Cory R.
last_name: Dean
citation:
ama: 'Chen S, Yankowitz M, Polshyn H, et al. Correlated insulating and superconducting
phases in twisted bilayer graphene. In: APS March Meeting 2019. Vol 64.
American Physical Society; 2019.'
apa: 'Chen, S., Yankowitz, M., Polshyn, H., Watanabe, K., Taniguchi, T., Graf, D.
E., … Dean, C. R. (2019). Correlated insulating and superconducting phases in
twisted bilayer graphene. In APS March Meeting 2019 (Vol. 64). Boston,
MA, United States: American Physical Society.'
chicago: Chen, Shaowen, Matthew Yankowitz, Hryhoriy Polshyn, Kenji Watanabe, Takashi
Taniguchi, David E. Graf, Andrea Young, and Cory R. Dean. “Correlated Insulating
and Superconducting Phases in Twisted Bilayer Graphene.” In APS March Meeting
2019, Vol. 64. American Physical Society, 2019.
ieee: S. Chen et al., “Correlated insulating and superconducting phases in
twisted bilayer graphene,” in APS March Meeting 2019, Boston, MA, United
States, 2019, vol. 64, no. 2.
ista: 'Chen S, Yankowitz M, Polshyn H, Watanabe K, Taniguchi T, Graf DE, Young A,
Dean CR. 2019. Correlated insulating and superconducting phases in twisted bilayer
graphene. APS March Meeting 2019. APS: American Physical Society, Bulletin of
the American Physical Society, vol. 64, R14.00004.'
mla: Chen, Shaowen, et al. “Correlated Insulating and Superconducting Phases in
Twisted Bilayer Graphene.” APS March Meeting 2019, vol. 64, no. 2, R14.00004,
American Physical Society, 2019.
short: S. Chen, M. Yankowitz, H. Polshyn, K. Watanabe, T. Taniguchi, D.E. Graf,
A. Young, C.R. Dean, 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: 2022-02-04T13:48:04Z
date_published: 2019-03-01T00:00:00Z
date_updated: 2022-02-08T10:24:13Z
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/R14.4
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'
related_material:
link:
- relation: used_in_publication
url: https://arxiv.org/abs/1808.07865
status: public
title: Correlated insulating and superconducting phases in twisted bilayer graphene
type: conference
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
volume: 64
year: '2019'
...
---
_id: '10723'
abstract:
- lang: eng
text: In monolayer graphene, the interplay of electronic correlations with the internal
spin- and valley- degrees of freedom leads to a complex phase diagram of isospin
symmetry breaking at high magnetic fields. Recently, Wei et al. (Science (2018))
demonstrated that spin waves can be electrically generated and detected in graphene
heterojunctions, allowing direct experiment access to the spin degree of freedom.
Here, we apply this technique to high quality graphite-gated graphene devices
showing robust fractional quantum Hall phases and isospin phase transitions. We
use an edgeless Corbino geometry to eliminate the contributions of edge states
to the spin-wave mediated nonlocal voltage, allowing unambiguous identification
of spin wave transport signatures. Our data reveal two phases within the ν = 1
plateau. For exactly ν=1, charge is localized but spin waves propagate freely
while small carrier doping completely quenches the low-energy spin-wave transport,
even as those charges remain localized. We identify this new phase as a spin textured
electron solid. We also find that spin-wave transport is modulated by phase transitions
in the valley order that preserve spin polarization, suggesting that this technique
is sensitive to both spin and valley order.
article_number: P01.00004
article_processing_charge: No
author:
- first_name: Haoxin
full_name: Zhou, Haoxin
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: Takashi
full_name: Tanaguchi, Takashi
last_name: Tanaguchi
- first_name: Kenji
full_name: Watanabe, Kenji
last_name: Watanabe
- first_name: Andrea
full_name: Young, Andrea
last_name: Young
citation:
ama: 'Zhou H, Polshyn H, Tanaguchi T, Watanabe K, Young A. Spin wave transport through
electron solids and fractional quantum Hall liquids in graphene. In: APS March
Meeting 2019. Vol 64. American Physical Society; 2019.'
apa: 'Zhou, H., Polshyn, H., Tanaguchi, T., Watanabe, K., & Young, A. (2019).
Spin wave transport through electron solids and fractional quantum Hall liquids
in graphene. In APS March Meeting 2019 (Vol. 64). Boston, MA, United States:
American Physical Society.'
chicago: Zhou, Haoxin, Hryhoriy Polshyn, Takashi Tanaguchi, Kenji Watanabe, and
Andrea Young. “Spin Wave Transport through Electron Solids and Fractional Quantum
Hall Liquids in Graphene.” In APS March Meeting 2019, Vol. 64. American
Physical Society, 2019.
ieee: H. Zhou, H. Polshyn, T. Tanaguchi, K. Watanabe, and A. Young, “Spin wave transport
through electron solids and fractional quantum Hall liquids in graphene,” in APS
March Meeting 2019, Boston, MA, United States, 2019, vol. 64, no. 2.
ista: 'Zhou H, Polshyn H, Tanaguchi T, Watanabe K, Young A. 2019. Spin wave transport
through electron solids and fractional quantum Hall liquids in graphene. APS March
Meeting 2019. APS: American Physical Society vol. 64, P01.00004.'
mla: Zhou, Haoxin, et al. “Spin Wave Transport through Electron Solids and Fractional
Quantum Hall Liquids in Graphene.” APS March Meeting 2019, vol. 64, no.
2, P01.00004, American Physical Society, 2019.
short: H. Zhou, H. Polshyn, T. Tanaguchi, K. Watanabe, 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: 2022-02-04T12:14:02Z
date_published: 2019-03-01T00:00:00Z
date_updated: 2022-02-04T13:59:47Z
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/P01.4
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: Spin wave transport through electron solids and fractional quantum Hall liquids
in graphene
type: conference
user_id: 8b945eb4-e2f2-11eb-945a-df72226e66a9
volume: 64
year: '2019'
...