2020 New's Items

Half-magnetization plateau and the origin of threefold symmetry breaking in an electrically switchable triangular antiferromagnet

S. C. Haley
S. F. Weber
T. Cookmeyer
D. E. Parker
E. Maniv
N. Maksimovic
C. John
S. Doyle
A. Maniv
S. K. Ramakrishna
A. P. Reyes
J. Singleton
J. E. Moore
J. B. Neaton
J. G. Analytis
2020

We perform high-field magnetization measurements on the triangular lattice antiferromagnet Fe1/3NbS2. We observe a plateau in the magnetization centered at approximately half the saturation magnetization over a wide range of temperature and magnetic...

Selective CO2 electrocatalysis at the pseudocapacitive nanoparticle/ordered-ligand interlayer

Kim D
Yu S
Zheng F
Roh I
Li Y
Louisia S
Qi Z
Somorjai GA
Frei H
Wang L-W
Yang P
2020

Enzymes feature the concerted operation of multiple components around an active site, leading to exquisite catalytic specificity. Realizing such configurations on synthetic catalyst surfaces remains elusive. Here, we report a nanoparticle/ordered-ligand interlayer that contains a multi-component catalytic pocket for high-specificity CO2 electrocatalysis. The nanoparticle/ordered-ligand interlayer comprises a metal nanoparticle surface and a detached layer of ligands in its vicinity. This interlayer possesses unique pseudocapacitive characteristics where...

Integrating the Fields of Catalysis: Active Site Engineering in Metal Cluster, Metal Organic Framework and Metal Single

Zhiyuan Qi
Luning Chen
Shuchen Zhang
Ji Su
Gabor A. Somorjai
2020

Research evolved using nanoparticles synthesized and characterized under reaction conditions opened the door to study all three fields of catalysis: heterogeneous, homogenous, and enzyme. Fundamental studies of catalytic reactions ranging from hydrogenation to understand Fischer-Tropsch synthesis and isomerization ultimately led to the integration of three fields of catalysis. Our recent work on bridging heterogeneous, homogenous, and enzymatic catalysis was present including functionalization of dendrimer encapsulated metal clusters surface for lactonization, active site engineering...

Precise Control of Molecular Self-Diffusion in Isoreticular and Multivariate Metal-Organic Frameworks

Popp TM
Plantz AZ
Yaghi OM
Reimer JA
2020

Understanding the factors that affect self-diffusion in isoreticular and multivariate (MTV) MOFs is key to their application in drug delivery, separations, and heterogeneous catalysis. Here, we measure the apparent self-diffusion of solvents saturated within the pores of large single crystals of MOF-5, IRMOF-3 (amino-functionalized MOF-5), and 17 MTV-MOF-5/IRMOF-3 materials at various mole fractions. We find that the apparent self-diffusion coefficient of N,N-dimethylformamide (DMF) may be tuned linearly between the diffusion coefficients of MOF-5 and IRMOF-...

Evaporated tellurium thin films for p-type field-effect transistors and circuits

Zhao C
Tan C
Lien DH
Song X
Amani M
Hettick M
Nyein HY
Yuan Z
Li L
Scott MC
Javey A
2020

There is an emerging need for semiconductors that can be processed at near ambient temperature with high mobility and device performance. Although multiple n-type options have been identified, the development of their p-type counterparts remains limited. Here, we report the realization of tellurium thin films through thermal evaporation at cryogenic temperatures for fabrication of high-performance wafer-scale p-type field-effect transistors. We achieve an effective hole mobility of ~35 cm2 V−1 s−1, on/off...

Using a Recurrent Neural Network to Reconstruct Quantum Dynamics of a Superconducting Qubit from Physical Observations

Flurin E
Martin LS
Hacohen-Gourgy S
Siddiqi I
2020

At its core, quantum mechanics is a theory developed to describe fundamental observations in the spectroscopy of solids and gases. Despite these practical roots, however, quantum theory is infamous for being highly counterintuitive, largely due to its intrinsically probabilistic nature. Neural networks have recently emerged as a powerful tool that can extract nontrivial correlations in vast datasets. These networks routinely outperform state-of-the-art techniques in language translation, medical diagnosis, and image recognition. It remains to be seen if neural networks can be trained...

Optical Imaging and Spectroscopy of Atomically Precise Armchair Graphene Nanoribbons

Zhao S
Barin GB
Cao T
Overbeck J
Darawish R
Lyu T
Drapcho S
Wang S
Dumslaff T
Narita A
Calame M
Müllen K
Louie SG
Ruffieux P
Fasel R
Wang F
2020

We report the optical imaging and absorption spectroscopy on atomically precise armchair graphene nanoribbons (GNRs) on insulating fused silica substrates. This is achieved by controlling light polarization on macroscopically aligned GNRs which greatly enhances the optical contrast of the submonolayer GNRs on the insulating substrates. We measure the linear absorption spectra of 7-armchair and 9-armchair GNRs in this study, and the experimental data agree qualitatively with ab inito calculation results. The polarization spectroscopy technique enables an unambiguous optical...

Photoinduced phase separation in the lead halides is a polaronic effect

Limmer DT
Ginsberg NS
2020
We present a perspective on recent observations of the photoinduced phase separation of halides in multi-component lead-halide perovskites. The spontaneous phase separation of an initial homogeneous solid solution under steady-state illumination conditions is found experimentally to be reversible, stochastic, weakly dependent on morphology, yet strongly dependent on composition and thermodynamic state. Regions enriched in a specific halide species that form upon phase separation are self-limiting in size, pinned to specific compositions, and grow in number in proportion to the steady-state...

Strong correlations and orbital texture in single-layer 1T-TaSe2

Chen Y
Ruan W
Wu M
Tang S
Ryu H
Tsai HZ
Lee RL
Kahn S
Liou F
Jia C
Albertini OR
Xiong H
Jia T
Liu Z
Sobota JA
Liu AY
Moore JE
Shen ZX
Louie SG
Mo SK
Crommie MF
2020

Strong electron correlation can induce Mott insulating behaviour and produce intriguing states of matter such as unconventional superconductivity and quantum spin liquids. Recent advances in van der Waals material synthesis enable the exploration of Mott systems in the two-dimensional limit. Here we report characterization of the local electronic properties of single- and few-layer 1T-TaSe2 via spatial- and momentum-resolved spectroscopy involving scanning tunnelling microscopy and angle-resolved photoemission. Our results indicate that electron correlation...

Revealing the Local Electronic Structure of a Single-Layer Covalent Organic Framework through Electronic Decoupling

Rizzo DJ
Dai Q
Bronner C
Veber GC
Smith BJ
Matsumoto M
Thomas S
Nguyen GD
Forrester PR
Zhao W
Jørgensen JH
Dichtel WR
Fischer FR
Li H
Brédas JL
Crommie MF
2020

Covalent organic frameworks (COFs) are molecule-based 2D and 3D materials that possess a wide range of mechanical and electronic properties. We have performed a joint experimental and theoretical study of the electronic structure of boroxine-linked COFs grown under ultrahigh vacuum conditions and characterized using scanning tunneling spectroscopy on Au(111) and hBN/Cu(111) substrates. Our results show that a single hBN layer electronically decouples the COF from the metallic substrate, thus suppressing substrate-induced broadening and revealing new features in the COF electronic...