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Publications

Semiclassical theory of the tunneling anomaly in partially spin-polarized compressible quantum Hall states

Cornell Affiliated Author(s)
Author
Debanjan Chowdhury
B. Skinner
P.A. Lee
Abstract

Electron tunneling into a system with strong interactions is known to exhibit an anomaly, in which the tunneling conductance vanishes continuously at low energy due to many-body interactions. Recent measurements have probed this anomaly in a quantum Hall bilayer of the half-filled Landau level, and shown that the anomaly apparently gets stronger as the half-filled Landau level is increasingly spin polarized.

Journal
Physical Review B
Date Published
Funding Source
PHY-1607611
FG02-03ER46076
GBMF-4303
DE-SC0001088
Group (Lab)
Debanjan Chowdhury Group

Valley-Selective Exciton Bistability in a Suspended Monolayer Semiconductor

Cornell Affiliated Author(s)
Author
H. Xie
S. Jiang
J. Shan
K.F. Mak
Abstract

We demonstrate robust optical bistability, the phenomenon of two well-discriminated stable states depending upon the history of the optical input, in fully suspended monolayers of WSe2 at low temperatures near the exciton resonance. Optical bistability has been achieved under continuous-wave optical excitation that is red-detuned from the exciton resonance at an intensity level of 103 W/cm2. The observed bistability is originated from a photothermal mechanism, which provides both optical nonlinearity and passive feedback, two essential elements for optical bistability.

Journal
Nano Letters
Date Published
Funding Source
DMR-1410407
FA9550-16-1-0249
W911NF-17-1-0605
Group (Lab)
Jie Shan Group
Kin Fai Mak Group

Mixed-valence insulators with neutral Fermi surfaces

Cornell Affiliated Author(s)
Author
Debanjan Chowdhury
I. Sodemann
T. Senthil
Abstract

Samarium hexaboride is a classic three-dimensional mixed valence system with a high-Temperature metallic phase that evolves into a paramagnetic charge insulator below 40 K. A number of recent experiments have suggested the possibility that the low-Temperature insulating bulk hosts electrically neutral gapless fermionic excitations.

Journal
Nature Communications
Date Published
Funding Source
DE-SC0008739
GBMF-4303
Group (Lab)
Debanjan Chowdhury Group

Density and electron density of aqueous cryoprotectant solutions at cryogenic temperatures for optimized cryoprotection and diffraction contrast

Cornell Affiliated Author(s)
Author
T.J. Tyree
R. Dan
R.E. Thorne
Abstract

The glass-phase densities at T = 77 K of aqueous solutions of the common cryoprotective agents (CPAs) methanol, ethanol, 2-propanol, glycerol, 2-methyl-2,4-pentanediol (MPD), ethylene glycol, polyethylene glycol 200 and polypropylene glycol 425 were measured as a function of CPA concentration. Individual drops with volumes as small as ∼65 pl were rapidly cooled to achieve the glass phase, and their densities at T = 77 K were determined by cryoflotation.

Journal
Acta Crystallographica Section D: Structural Biology
Date Published
Group (Lab)
Robert Thorne Group

Electric-field switching of two-dimensional van der Waals magnets

Cornell Affiliated Author(s)
Author
S. Jiang
J. Shan
K.F. Mak
Abstract

Controlling magnetism by purely electrical means is a key challenge to better information technology 1 . A variety of material systems, including ferromagnetic (FM) metals 2-4, FM semiconductors 5, multiferroics 6-8 and magnetoelectric (ME) materials 9,10, have been explored for the electric-field control of magnetism. The recent discovery of two-dimensional (2D) van der Waals magnets 11,12 has opened a new door for the electrical control of magnetism at the nanometre scale through a van der Waals heterostructure device platform 13 .

Journal
Nature Materials
Date Published
Funding Source
DMR-1410407
FA9550-16-1-0249
FA9550-14-1-0268
W911NF-17-1-0605
Group (Lab)
Jie Shan Group
Kin Fai Mak Group

Mechanisms of oxide growth during the combustion of Al:Zr nanolaminate foils

Cornell Affiliated Author(s)
Author
K.R. Overdeep
H. Joress
L. Zhou
K.J.T. Livi
S.C. Barron
M.D. Grapes
K.S. Shanks
D.S. Dale
M.W. Tate
H.T. Philipp
Sol Gruner
T.C. Hufnagel
T.P. Weihs
Abstract

Reactive metal nanolaminates, most notably aluminum/zirconium composites, have been developed as fuels to aid combustion in explosive formulations. Thus far, however, their energy density is limited by incomplete oxidation. An in situ x-ray diffraction (XRD) study was performed on a 40 µm thick Al:Zr (atomic ratio 1:1) multilayer foil to track the growth of reaction products during ignition, combustion, and cooling (over approximately 5 s) to determine the mechanisms that prevent complete combustion from occurring.

Journal
Combustion and Flame
Date Published
Funding Source
DMR-1332208
N0004-07-1-0740
DE-FG02-10ER46693
DE-SC0016035
HDTRA1-11-1-0063
HDTRA1-15-1-0006
Group (Lab)
Sol M. Gruner Group

Controlling surface carrier density by illumination in the transparent conductor La-doped BaSnO3

Cornell Affiliated Author(s)
Author
E.B. Lochocki
H. Paik
M. Uchida
D.G. Schlom
K.M. Shen
Abstract

LaxBa1-xSnO3 is a promising transparent conducting oxide whose high mobility facilitates potential applications in transparent electronics, oxide electronics, and power electronics. Here, we report quantitative comparisons between angle-resolved photoemission and density functional theory, demonstrating a close agreement between calculations and the measured bulk electronic structure. Further measurements reveal upward band bending at the film-vacuum interface, while ultraviolet (UV) exposure is found to increase the surface electron density, similar to other oxides.

Journal
Applied Physics Letters
Date Published
Funding Source
DMR-1120296
DMR-1539918
18H01866
Group (Lab)
Kyle Shen Group

Nonzero Berry phase in quantum oscillations from giant Rashba-type spin splitting in LaTiO3/SrTiO3 heterostructures

Cornell Affiliated Author(s)
Author
M. Veit
R. Arras
B. Ramshaw
R. Pentcheva
Y. Suzuki
Abstract

The manipulation of the spin degrees of freedom in a solid has been of fundamental and technological interest recently for developing high-speed, low-power computational devices. There has been much work focused on developing highly spin-polarized materials and understanding their behavior when incorporated into so-called spintronic devices. These devices usually require spin splitting with magnetic fields. However, there is another promising strategy to achieve spin splitting using spatial symmetry breaking without the use of a magnetic field, known as Rashba-type splitting.

Journal
Nature Communications
Date Published
Funding Source
G03
SFB/TRR 80
1157490
Group (Lab)
Brad Ramshaw Group

Dynamical susceptibility near a long-wavelength critical point with a nonconserved order parameter

Cornell Affiliated Author(s)
Author
A. Klein
S. Lederer
Debanjan Chowdhury
E. Berg
A.V. Chubukov
Abstract

We study the dynamic response of a two-dimensional system of itinerant fermions in the vicinity of a uniform (Q=0) Ising nematic quantum critical point of d-wave symmetry. The nematic order parameter is not a conserved quantity, and this permits a nonzero value of the fermionic polarization in the d-wave channel even for vanishing momentum and finite frequency: Π(q=0,Ωm)≠0.

Journal
Physical Review B
Date Published
Funding Source
1523036
Group (Lab)
Debanjan Chowdhury Group

Computation of a Theoretical Membrane Phase Diagram and the Role of Phase in Lipid-Raft-Mediated Protein Organization

Cornell Affiliated Author(s)
Author
E.D. Mitra
S.C. Whitehead
D. Holowka
B. Baird
J.P. Sethna
Abstract

Lipid phase heterogeneity in the plasma membrane is thought to be crucial for many aspects of cell signaling, but the physical basis of participating membrane domains such as "lipid rafts" remains controversial. Here we consider a lattice model yielding a phase diagram that includes several states proposed to be relevant for the cell membrane, including microemulsion - which can be related to membrane curvature - and Ising critical behavior. Using a neural-network-based machine learning approach, we compute the full phase diagram of this lattice model.

Journal
Journal of Physical Chemistry B
Date Published
Funding Source
2T32GM008267
DMR-1312160
DMR-1719490
R01-AI018306
R01GM117552
Research Area
Group (Lab)
James Sethna Group