compilation | Feng Weiwei
Nature, 15 September 2022, VOL 609, ISSUE 7927
《Nature》September 15, 2022, Volume 609, Issue 7927
PhysicsPhysics
Femtosecond laser writing of Lithiumniobate ferroelectric nanodomains
femtosecond laser writes lithium niobate ferroelectric nanodomains
▲ Author: Xiaoyi Xu, Tianxin Wang, Pengcheng Chen, Chao Zhou, Jianan Ma, Dunzhao Wei, Huijun Wang, Ben Niu, Xinyuan Fang, Di Wu, Shining Zhu, Min Gu, Min Xiao & Yong Zhang
▲ Link:
https://www.nature.com/articles/s41586-022-05042-z
▲ Abstract:
Lithium niobate (LiNbO3) is a promising optical communication and quantum photonic chip material. The authors demonstrate a non-reciprocal near-infrared laser writing technique for reconstructible three-dimensional ferroelectric domain engineering with nanoscale resolution in LiNbO3. The method proposed by
is based on the laser-induced electric field, and the domain structure in the crystal can be written or erased according to the direction of the laser writing. This method provides a way for the controllable nanodomain engineering of transparent ferroelectric crystals such as LiNbO3, and has potential application value in high-efficiency mixing, high-frequency acoustic resonators, and large-capacity nonvolatile ferroelectric memory .
▲ Abstract:
Lithium niobate (LiNbO3) is viewed as a promising material for optical communications and quantum photonic chips. Here we demonstrate a non-reciprocal near-infrared laser-writing technique for reconfigurable three-dimensional ferroelectric domain engineering in LiNbO3 with nanoscale resolution. The proposed method is based on a laser-induced electric field that can either write or erase domain structures in the crystal, depending on the laser-writing direction. This approach offers a pathway for controllable nanoscale domain engineering in LiNbO3 and other transparent ferroelectric crystals, which has potential applications in high-efficiency frequency mixing, high-frequency acoustic resonators and high-capacity non-volatile ferroelectric memory.
Attosecond spectroscopy of size-resolved water clusters
size-resolved water mass clusters
▲ Author: Xiaochun Gong, Saijoscha Heck, Denis Jelovina, Conaill Perry, Kristina Zinchenko, Robert Lucchese & Hans Jakob Wrner
▲ Link:
htps://www.nature.com/articles/s41586-022-05039-8
▲ Abstract:
Electronic dynamics in water are fundamentally important to many phenomena, but in fact, research faces many conceptual and method challenges. The author introduces the at-second size resolution clustering spectrum to establish an understanding of the molecular level of at-second electron dynamics in water. They measured the effect of the addition of a single water molecule on the photodelay delay of the water cluster, and found that for the cluster containing 4 to 5 molecules, the delay continued to increase, while for larger clusters, the delay did not change much.
researchers have shown that these delays are proportional to the spatial expansion of the generated electron holes, which first increase with the size of the clusters, and then partially localize by the emergence of structural disorders of large clusters and large volumes of liquid water.
These results indicate that the sensitivity of the light separation delay to electron hole delocalization is unknown, and also indicate a direct link between the electron structure and the atsecond light separation kinetics. This result provides a new perspective for studying electron hole delocalization and its atsecond dynamics.
▲ Abstract:
Electron dynamics in water are of fundamental importance for a broad range of phenomenon, but their real-time study faces numerous conceptual and methodological challenges. Here we introduce attosecond size-resolved cluster spectroscopy and build up a molecular-level understanding of the attosecond electron dynamics in water. We measure the effect that the addition of single water molecules has on the photoionization time delays of water clusters. We find a continuous increase of the delay for clusters containing up to four to five molecules and little change towards larger clusters. We show that these delays are proportional to the spatial extension of the created electron hole, which first increases with cluster size and then partially localizes through the onset of structural disorder that is characteristic of large clusters and bulk liquid water. These results indicate a previously unknown sensitivity of photoionization delays to electronic-hole delocalization and indicate a direct link between electronic structure and attosen photoionization dynamics. Our results offer new perspectives for studying electron-hole delocalization and its attosen dynamics.
Extended Bose–Hubbard model with dipolar excitons
Extended Bose-Hubbard model with dipolar exciton
▲ Author: C. Lagoin, U. Bhattacharya, T. Grass, R. W. Chhajlany, T. Salamon, K. Baldwin, L. Pfeiffer, M. Lewenstein, M. Holzmann & F. Dubin
▲ Link:
https://www.nature.com/articles/s41586-022-05123-z
▲ Abstract:
Hubard's model is one of the most famous theoretical frameworks in condensed matter physics. It describes the strong correlation phase of interacting quantum particles confined to the lattice potential. For bosons, Hubbard Hamiltonian has been studied in-depth close-field interactions.
Experimentally, however, it is still elusive to obtain coupled for a longer distance. This marks the frontier towards the extended Bose-Hubard Hamiltonian, which makes it possible to isolate ordered phases in fractional dot fill. The authors achieve this Hamiltonian by limiting semiconductor dipole excitons in an artificial two-dimensional square lattice.
The strongest dipole repulsion force stabilizes the semi-filled state in the insulating state between the nearest neighbor lattice positions. This feature of the extended Bose-Hubbard model shows the theoretical characteristics of the order of checkerboard space. Therefore, this study highlights that dipole excitons enable controlled implementation of boson-like arrays with strong off-site interactions in lattices with programmable geometry and over 100 sites.
▲ Abstract:
The Hubbard model constitutes one of the most celebrated theoretical frameworks of condensed-matter physics. It describes strongly correlated phases of interacting quantum particles configured in lattice potentials. For bosses, the Hubbard Hamiltonian has been deeply scrutinized for short-range on-site interactions. However, accessing longer-range couples have remained extremely experimentally. This marks the frontier towards the extended Bose–Hubbard Hamiltonian, which enables insulating ordered phases at fractional lattice fillings. Here we implement this Hamiltonian by confining semiconductor diplomatic excitons in an artificial two-dimensional square lattice. Strong diploma repulsions between nearest-neighbour lattice sites then stabilize an insulating state at half filling. This characteristic feature of the extended Bose–Hubbard model exhibits the signatures theoretically expected for a chequerboard spatial order. Our work thus highlights that diplomar excitons enable controlled implementations of boson-like arrays with strong off-site interactions, in lattices with programmable geometries and more than 100 sites.
ChemistryChemistry
The first-principles phase diagram of monolayer nanoconfined water
First principle phase diagram of single-layer nanocompressed water
▲ Author: Venkat Kapil, Christoph Schran, Andrea Zen, Ji Chen, Chris J. Pickard & Angelos Michaelides
▲ Link:
htps://www.nature.com/articles/s41586-022-05036-x
▲ Abstract:
nanoscale cavity is everywhere, which is crucial to the daily phenomena of geology and biology. However, the properties of nanoscale water can be essentially different from those of volume water.
authors combined a series of calculation methods to achieve first-principles research on single-layer water in graphene channels. They found that monolayer water exhibited surprisingly abundant and diverse phase behaviors, highly sensitive to temperature and van der Waals pressure acting within nanochannels.
In addition to the non-monotonous change of melting temperature over 400 Kelvin multiple molecular phases, they also predicted a six-phase, which is an intermediate between solid and liquid, and a superionic phase with high conductivity that exceeds the battery material. It is worth noting that this suggests that nanoconstraints may be a promising pathway to achieve phonon behavior under easily accessible conditions.
▲ Abstract:
Water in nanoscale cavities is ubiquitous and of central importance to every day phenomenon in geology and biology. However, the properties of nanoscale water can be substantially different from those of bulk water. Here we combine a range of computing approaches to enable a first-principles-level investigation of a single layer of water within a graphene-like channel. We find that monolayer water exhibitions surprisingly rich and diverse phase behavior that is highly sensitive to temperature and the van der Waals pressure acting within the nanochannel. In addition to multiple molecular phases with melting temperatures varying non-monotonically by more than 400 kelvins with pressure, we predict a hexatic phase, which is an intermediate between a solid and a liquid, and a superionic phase with a high electric conductivity exceeding that of battery materials. Notably, this suggests that nanoconfinement could be a promising route towards superionic behavior under easily accessible conditions.
ClimatologyClimate
A year-round satellite sea-ice thickness record from CryoSat-2
CryoSat-2's full-year satellite sea ice thickness record
▲ Author: Jack C. Landy, Geoffrey J. Dawson, Michel Tsamados, Mitchell Bushuk, Julienne C. Stroeve, Stephen E. L. Howell, Thomas Krumpen, David G. Babb, Alexander S. Komarov, Harry D. B. S. Heorton, H. Jakob Belter & Yevgeny Aksenov
▲ Link:
https://www.nature.com/articles/s41586-022-05058-5
▲ Abstract:
As the climate warms, Arctic sea ice is decreasing at an unprecedented rate in at least a thousand years. As the melting of the ice sheet causes increased commercial interests in the Arctic, it becomes more variable and mobile, which increases the security risks for sea users.
However, satellite observations of sea ice thickness are currently not possible during this critical ice melting period from May to September. During this period, satellite observations are most valuable for applications such as seasonal predictions due to the significant challenges facing processing altimeter data.
authors used deep learning and numerical simulations of the radar altimeter response of the polar altimeter built by the European Space Agency to overcome these challenges and generated a pan- Arctic sea ice thickness dataset for the Arctic melting period.
CryoSat-2 observations captured the spatial and temporal patterns of ice melting rates recorded by independent sensors and matched the time series of simulated sea ice volumes by Pan Arctic Ice Ocean Simulation and Assimilation System Reanalysis.
2011 - At the beginning of the melting season in May 2020, the thickness of the Arctic sea ice was 1.87±0.10 meters; at the end of the melting season in August, the thickness of the sea ice was 0.82±0.11 meters. This year-round record of sea ice thickness provides an opportunity to understand feedback on Arctic climate on different time scales.
▲ Abstract:
Arctic sea ice is diminishing with climate warming at a rate unmatched for at least 1,000 years. As the receiving ice pack raises commercial interest in the Arctic, it has become more variable and mobile, which increases safety risks to maritime users5. Satellite observations of sea-ice thickness are currently unavailable During the cruel melt period from May to September, when they would be most valuable for applications such as seasonal forecasting, owing to major challenges in the processing of altimetry data. Here we use deep learning and numerical simulations of the CryoSat-2 ratar altimeter response to overcome these challenges and generate a pan-Arctic sea-ice thickness dataset for the Arctic melt period. CryoSat-2 observations capture the spatial and the temporal patterns of ice melting rates recorded by independent sensors and match the time series of sea-ice volume modelled by the Pan-Arctic Ice Ocean Modelling and Assimilation System reanalysis. Between 2011 and 2020, Arctic sea-ice thickness was 1.87±0.10m at the start of the melting season in May and 0.82±0.11m by the end of the melting season in August. Our year-round sea-ice thickness record unlocks opportunities for understanding Arctic climate feedbacks on different timescales.
geologyGeology
Rapid shifting of a deep magmatic source at Fagradalsfjall volcano, Iceland
Iceland's deep volcano Iceland's Fagradal volcano Magma 3source fast movement
▲ Author: Sæmundur A. Halldórsson, Edward W. Marshall, Alberto Caracciolo et al.
▲ Link:
https://www.nature.com/articles/s41586-022-04981-x
▲ Abstract:
Iceland Rift Event revealed the role of concentrated crustal magma reservoirs and lateral magma migration, as well as important characteristics of ridge magma activity in the ocean. The result of this shallow crust processing of magma is that in the uppermost mantle and the lowermost crust, features traced back to the origin, evolution and migration of the melt are overlapped. The authors provide unique insights into the process that occurs in the region through a comprehensive petrology and geochemistry study of the 2021 Gradal volcanic eruption in the Reckjans Peninsula in Iceland.
geochemical analysis of basalt erupted 50 days before eruption, combined with related gas emissions, reveals its direct source of magma storage zone near Moho District. Geochemical indicators represent different mantle compositions and melting conditions, and their speed of change is incomparable to a single basalt eruption worldwide.
Initially, the erupted lava was mainly composed of melts from the shallowest mantle, but in the following three weeks, the magma was increasingly composed of deeper magma. This trend of abnormally rapid erupting components provides an unprecedented time record of magma mixing, filtering mantle signals, consistent with the treatment of near-Mojo melt lenses containing 107-108 cubic meters of basal magma. Through near-real-time investigation of this critical magma treatment area, a new understanding of the time scale and operating mode of the basalt magma system can be obtained.
▲ Abstract:
Recent Icelandic rifting events have illuminated the roles of centralized crustal magma reservoirs and lateral magma transport, important characteristics of mid-ocean ridge magmatism. A consequence of such shallow crustal processing of magmas is the overprinting of signatures that trace the origin, evolution and transport of melts in the uppermost mantle and lowermost crust. Here we present unique insights into processes occurring in this zone from integrated petrologic and geochemical studies of the 2021 Fagradalsfjall eruption on the Reykjanes Peninsula in Iceland. Geochemical analysis of basalts erupted during the first 50 days of the eruption, combined with associated gas emissions, reveal direct sourcing from a near-Moho magma storage zone. Geochemical proxies, which signify different mantle compositions and melting conditions, changed at a rate unparalleled for individual basaltic eruptions globally. Initially, the erupted lava was dominated by melts sourced from the shallowest mantle but over the following three weeks became increasingly dominated by magmas generated at a greater depth. This exceptionally rapid trend in erupted compositions provide an unprecedented temporal record of magma mixing that filters the mantle signal, consistent with processing in near-Moho melt lenses containing 107-108 m3 of basaltic magma. Exposing previously inaccessible parts of this key magma processing zone to near-real-time investigations provide new insights into the timescales and operational mode of basaltic magma systems.
