2023 New's Items

Long-range, non-local switching of spin textures in a frustrated antiferromagnet

Haley SC
Analytis JG
Moore JE
2023

Antiferromagnetic spintronics is an emerging area of quantum technologies that leverage the coupling between spin and orbital degrees of freedom in exotic materials. Spin-orbit interactions allow spin or angular momentum to be injected via electrical stimuli to manipulate the spin texture of a material, enabling the storage of information and energy. In general, the physical process is intrinsically local: spin is carried by an electrical current, imparted into the magnetic system, and the spin texture will then rotate in the region of current flow. In this study, we show that spin...

Topological quantum synchronization of fractionalized spins

Wächtler CW
Moore JE
2023

The gapped symmetric phase of the Affleck-Kennedy-Lieb-Tasaki (AKLT) model exhibits fractionalized spins at the ends of an open chain. We show that breaking SU(2) symmetry and applying a global spin-lowering dissipator achieves synchronization of these fractionalized spins\rev{, which remains protected even if the inversion symmetry is not preserved}. Additional local dissipators ensure convergence to the ground state manifold. In order to understand which aspects of this synchronization are robust within the entire Haldane-gap phase, we reduce the biquadratic term which eliminates...

Angle-resolved pair photoemission theory for correlated electrons

Devereaux TP
Shen Z-X
Moore JE
2023

In this paper, we consider the possibility and conditions for pair photoemission, whereby two incident photons emit pairs of electrons from a candidate material, as a method to measure and visualize electronic correlations. As opposed to double photoemission—where a single photon precipitates the ejection of a pair of electrons via a subsequent electron energy loss scattering process—we show that pair photoemission need not be limited to interference between initial photoelectrons and valence electrons and moreover can occur without the energy penalty of two work functions. This...

Symmetry-breaking pathway towards the unpinned broken helix

Donoway E
Sunko V
Moore JE
2023

One of the prime material candidates to host the axion insulator state is EuIn2As2. First-principles calculations predicted the emergence of this exotic topological phase based on the assumption of a collinear antiferromagnetic structure. However, neutron scattering...

Linear magneto-conductivity as a DC probe of time-reversal symmetry breaking

Sunko V
Orenstein J
Moore JE
2023

Several optical experiments have shown that in magnetic materials the principal axes of response tensors can rotate in a magnetic field. Here we offer a microscopic explanation of this effect, and propose a closely related DC transport phenomenon -- an off-diagonal \emph{symmetric} conductivity linear in a magnetic field, which we refer to as linear magneto-conductivity (LMC). Although LMC has the same functional dependence on magnetic field as the Hall effect, its origin is fundamentally different: LMC requires time-reversal symmetry to be broken even before a magnetic field is...

Converting Non-Equilibrium Charge Density into Spin Current

Vila M
Moore JE
2023

The interconversion between charge and spin degrees of freedom is of both fundamental and technological relevance in spintronics. While a non-equilibrium spin density and a charge current are related by the well known Rashba-Edelstein effect, here we theoretically model the generation of a time-dependent spin current due to a periodic modulation of the charge density, for example by a gate. By using the Boltzmann transport equation, we show that when the chemical potential is varied, a spin current is generated in the time scale it takes for the system to re-equilibrate in the new...

Structural evolution of water-in-propylene carbonate mixtures revealed by polarized Raman spectroscopy and molecular dynamics

Clark JB
Allen HC
Limmer DT
2023

The liquid structure of systems wherein water is limited in concentration or through geometry is of great interest in various fields such as biology, materials science, and electrochemistry. Here, we present a combined polarized Raman and molecular dynamics investigation of the structural changes that occur as water is added incrementally to propylene carbonate (PC), a polar, aprotic solvent that is important in lithium-ion batteries. Polarized Raman spectra of PC solutions were collected for water mole fractions 0.003 ≤ χwater ≤ 0....

Probing reaction channels via reinforcement learning

Liang S
Yang C
Limmer DT
2023

Chemical reactions are dynamical processes involving the correlated reorganization of atomic configurations, driving the conversion of an initial reactant into a result product. By virtue of the metastability of both the reactants and products, chemical reactions are rare events, proceeding fleetingly. Reaction pathways can be modelled probabilistically by using the notion of reactive density in the phase space of the molecular system. Such density is related to a function known as the committor function, which describes the likelihood of a configuration evolving to one of the nearby...

Variational deep learning of equilibrium transition path ensembles

Singh AN
Limmer DT
2023

We present a time-dependent variational method to learn the mechanisms of equilibrium reactive processes and efficiently evaluate their rates within a transition path ensemble. This approach builds off of the variational path sampling methodology by approximating the time-dependent commitment probability within a neural network ansatz. The reaction mechanisms inferred through this approach are elucidated by a novel decomposition of the rate in terms of the components of a stochastic path action conditioned on a transition. This decomposition affords an ability to resolve the typical...

Weak Temperature Dependence of the Relative Rates of Chlorination and Hydrolysis of N2O5 in NaCl–Water Solutions

Kregel SJ
Bertram TH
Limmer DT
2023

We have measured the temperature dependence of the ClNO2 product yield in competition with hydrolysis following N2O5 uptake to aqueous NaCl solutions. For NaCl–D2O solutions spanning 0.0054–0.21 M, the ClNO2 product yield decreases on average by only 4 ± 3% from 5 to 25 °C. Less reproducible measurements at 0.54–2.4 M NaCl also fall within this range. The ratio of the rate constants for chlorination and hydrolysis of N2O...