2025 New's Items

Large deviations of ionic currents in dilute electrolytes

Jafar Farhadi
David T. Limmer
2025

We evaluate the exponentially rare fluctuations of the ionic current for a dilute electrolyte by means of macroscopic fluctuation theory. We consider the fluctuating hydrodynamics of a fluid electrolyte described by a stochastic Poisson–Nernst–Planck equation. We derive the Euler–Lagrange equations that dictate the optimal concentration profiles of ions conditioned on exhibiting a given current, whose form determines the likelihood of that current in the long-time limit. For a symmetric electrolyte under small applied voltages, number density fluctuations are small, and ionic current...

Nonadiabatic Force Matching for Alchemical Free-Energy Estimation

Jorge L. Rosa-Raíces
David T. Limmer
2025

We propose a method to compute free-energy differences from nonadiabatic alchemical transformations by using flow-based generative models. The method, nonadiabatic force matching, hinges on estimating the dissipation along an alchemical switching process in terms of a nonadiabatic force field that can be learned through stochastic flow matching. The learned field can be used in conjunction with short-time trajectory data to evaluate upper and lower bounds on the alchemical free energy that variationally converge to the exact value if the field is optimal. Applying the method to...

Solvation of CaCl2 at the Water–Vapor Interface Revealed by Ambient Pressure X-ray Photoelectron Spectroscopy

Andreas Siebert
Kritanjan Polley
Shane W. Devlin
N. Isaac Zakaria
Mauricio Lopez Luna
Nykita Rustad
David T. Limmer
Monika Blum
2025

The determination of ion concentrations at aqueous interfaces is of paramount importance for the precise modeling of atmospheric reactions. Despite their significant concentrations observed in bulk sea spray aerosol studies, the concentration of Ca2+ ions at the liquid–vapor interface remains unclear. Ambient pressure X-ray photoelectron spectroscopy measurements performed on a liquid flat sheet combined with molecular dynamics simulations reveal the solvation structure and density profiles of Ca2+ and Cl–...

Spin Polarization from Circularly Polarized Light Induced Charge Transfer

Sindhana Pannir-Sivajothi
David T. Limmer
2025

We show how a spin polarization can be generated through the photo-induced electron transfer of an achiral donor-acceptor complex following chiral light excitation. In particular, we illustrate the basic energetic and symmetry requirements for chirality induced spin selectivity where the chirality emerges from the electronic degrees of freedom following excitation with circularly polarized light. We study this effect in a simple model of a metalloporphyrin complex with an axial acceptor ligand using quantum mechanical rate theories and numerical simulations. We find that the spin...

Epitaxial strain tuning of Er3+ in ferroelectric thin films

Rafaela M. Brinn
Peter Meisenheimer
Medha Dandu
Elyse Barré
Piush Behera
Archana Raja
Ramamoorthy Ramesh
Paul Stevenson
2025

Er3+ color centers are promising candidates for quantum science and technology due to their long electron and nuclear spin coherence times, as well as their desirable emission wavelength. By selecting host materials with suitable, controllable properties, we introduce new parameters that can be used to tailor the Er3+ emission spectrum. PbTiO3 is a well-studied ferroelectric material with known methods of engineering different domain configurations through epitaxial strain. By distorting the structure of Er3+-doped PbTiO3 thin films...

Graphene-driven correlated electronic states in one dimensional defects within WS2

Antonio Rossi
John C. Thomas
Johannes T. Küchle
Elyse Barré
Zhuohang Yu
Da Zhou
Shalini Kumari
Hsin-Zon Tsai
Ed Wong
Chris Jozwiak
Aaron Bostwick
Joshua A. Robinson
Mauricio Terrones
Archana Raja
Adam Schwartzberg
D. Frank Ogletree
Jeffrey B. Neaton
Michael F. Crommie
Francesco Allegretti
Willi Auwärter
Eli Rotenberg
Alexander Weber-Bargioni
2025

Tomonaga-Luttinger liquid (TLL) behavior in one-dimensional systems has been predicted and shown to occur at semiconductor-to-metal transitions within two-dimensional materials. Reports of one-dimensional defects hosting a Fermi liquid or a TLL have suggested a dependence on the underlying substrate, however, unveiling the physical details of electronic contributions from the substrate require cross-correlative investigation. Here, we study TLL formation within defectively engineered WS2 atop graphene, where band structure and the atomic environment is...

Long-lived photoinduced polar states in metal halide perovskites

Yixuan Dou
Xiaoming Wang
Nicholas W. G. Smith
Piush Behera
Rathsara Herath Mudiyanselage
Burak Guzelturk
Donald A. Walko
Yannick Pleimling
Sunhao Liu
Nicholas Nici
Carla Slebodnick
Bogdan Dryzhakov
Bin Hu
Archana Raja
Ramamoorthy Ramesh
Giti A. Khodaparast
Yanfa Yan
Lina Quan
2025

Ferroic polarization in hybrid perovskites is crucial for enhancing photovoltaic performance and developing potential electronic applications. Controlling ferroic polarization with an optical field enables probing of ferroic polarization without the unwanted interface ionic effects caused by electronic contacts. This study employs ultrafast near-infrared photoexcitation to control dynamic structural transitions in soft single crystalline hybrid Cu (II) halide perovskites, achieving a long-lived polar state (beyond 104 s) at room temperature. We probe...

Local Interface Effects Modulate Global Charge Order and Optical Properties of 1T–TaS2/1H–WSe2 Heterostructures

Samra Husremović
Valerie S. McGraw
Medha Dandu
Lilia S. Xie
Sae Hee Ryu
Oscar Gonzalez
Shannon S. Fender
Madeline Van Winkle
Karen C. Bustillo
Takashi Taniguchi
Kenji Watanabe
Chris Jozwiak
Aaron Bostwick
Eli Rotenberg
Archana Raja
Katherine Inzani
D. Kwabena Bediako
2025

1T–TaS2 is a layered charge density wave (CDW) crystal exhibiting sharp phase transitions and associated resistance changes. These resistance steps could be exploited for information storage, underscoring the importance of controlling and tuning the CDW states. Given the importance of out-of-plane interactions in 1T–TaS2, modulating interlayer interactions by heterostructuring is a promising method for tailoring CDW phase transitions. In this work, we investigate the optical and electronic properties of...

Optomechanical Tuning of Second Harmonic Generation Anisotropy in Janus MoSSe/MoS2 Heterostructures

Kunyan Zhang
Kunyan Zhang
Nguyen T. Hung
Tianyi Zhang
Elyse Barré
Riichiro Saito
Jing Kong
Archana Raja
Shengxi Huang
2025

Symmetry breaking in van der Waals materials enables the realization of quantum states and advanced device functionalities. Janus transition-metal dichalcogenides (TMDs) exhibit distinctive nonlinear optical properties due to their broken out-of-plane mirror symmetry. However, the dynamic control of second harmonic generation (SHG) anisotropy and resonance behavior via optical excitation remains elusive. In this work, we investigate the SHG response of Janus MoSSe/MoS2 heterostructures with 2H and 3R stackings. We can tune the SHG response by varying the incident photon...

Exploring the soft cradle effect and ionic transport mechanisms in the LiMXCl4 superionic conductor family

KyuJung Jun
Grace Wei
Xiaochen Yang
Yu Chen
Gerbrand Ceder
2025

Lithium-ion conductors with high ionic conductivity and electrochemical stability are critical for enabling safe, energy-dense all-solid-state batteries. LiMOCl4 (M = Nb/Ta) recently achieved impressive lithium-ion conductivity of 12.4 mS/cm at room temperature. However, the maximum possible ionic conductivity in this framework and the mechanisms driving such fast diffusion remain unclear. By substituting different cations (M) and anions (X) into LiMXCl4, we find that fluoro-chlorides may achieve higher stability without sacrificing...