The ground state properties of correlated electron systems can be extraordinarily sensitive to external stimuli, such as temperature, strain, and electromagnetic fields, offering abundant platforms for functional materials. We present a metastable and reversible photoinduced ferromagnetic transition in strained films of the doped manganite La2/3Ca1/3MnO3 (LCMO). Using the novel multi-messenger combination of atomic force microscopy, cryogenic scanning near-field optical microscopy, magnetic force microscopy, and ultrafast laser excitation, we demonstrate both "writing" and "erasing" of a metastable ferromagnetic metal phase with nanometer-resolved finesse. By tracking both optical conductivity and magnetism at the nano-scale, we reveal how spontaneous strain underlies the thermal stability, persistence, and reversal of this photoinduced metal. Our firstprinciples electronic structure calculations reveal how an epitaxially engineered Jahn-* These authors contributed equally to the present work. Corresponding author: † am4734@columbia.edu 2 Teller distortion can stabilize nearly degenerate antiferromagnetic insulator and ferromagnetic metal phases. We propose a Ginzburg-Landau description to rationalize the co-active interplay of strain, lattice distortion, and magnetism we resolve in strained LCMO, thus guiding future functional engineering of epitaxial oxides like manganites into the regime of phase-programmable materials. Ultrafast all-optical control of the insulator-metal transition in correlated electron systems 1 remains a coveted route towards reconfigurable functional materials. 2 Although transient photoinduced phase transitions can expose interactions among competing orders in complex systems, 3 persistent all-optical and reversible switching is desirable for ondemand device functionalities. 4 For example, the colossal magnetoresistive (CMR) manganites (AE1-xRExMnO3, AE: alkali earth, RE: rare earth) show magnetic and electronic properties that depend strongly on the microscopic geometrical configuration of the comprising MnO6 octahedral network. 5-8 This pliancy affords fertile ground for photoinduced manipulation of the equilibrium state. 9,10 In particular, the accompaniment of magnetism by spontaneous strain in Ca-doped La1-xCaxMnO3 11,12 raises the possibility for interplay between strain-coupling (often termed "coelasticity" 13 ) in this compound and the photoinduced insulator-metal transition. 14 Here we study a 26 nm thick La2/3Ca1/3MnO3 (LCMO) thin film grown on NdGaO3 (001) substrate. 15 Although first exhibiting a lowtemperature insulator to metal transition (IMT) common to the bulk system at T~250K, annealing these films in an oxygen environment coherently accommodates their epitaxy to the NdGaO3 substrate, stabilizing a persistent antiferromagnetic insulating (AFI) phase. 15 Strikingly, these insulating LCMO films show extreme susceptibility to ultra-short pulsed laser excitation (<200 fs), driving a persistent phase transition into a metallic state. 14 Although the IMT in rare-earth mangani...

[1] Single-column models (SCM) are useful test beds for investigating the parameterization schemes of numerical weather prediction and climate models. The usefulness of SCM simulations are limited, however, by the accuracy of the best estimate large-scale observations prescribed. Errors estimating the observations will result in uncertainty in modeled simulations. One method to address the modeled uncertainty is to simulate an ensemble where the ensemble members span observational uncertainty. This study first derives an ensemble of large-scale data for the Tropical Warm Pool International Cloud Experiment (TWP-ICE) based on an estimate of a possible source of error in the best estimate product. These data are then used to carry out simulations with 11 SCM and two cloud-resolving models (CRM). Best estimate simulations are also performed. All models show that moisture-related variables are close to observations and there are limited differences between the best estimate and ensemble mean values. The models, however, show different sensitivities to changes in the forcing particularly when weakly forced. The ensemble simulations highlight important differences in the surface evaporation term of the moisture budget between the SCM and CRM. Differences are also apparent between the models in the ensemble mean vertical structure of cloud variables, while for each model, cloud properties are relatively insensitive to forcing. The ensemble is further used to investigate cloud variables and precipitation and identifies differences between CRM and SCM particularly for relationships involving ice. This study highlights the additional analysis that can be performed using ensemble simulations and hence enables a more complete model investigation compared to using the more traditional single best estimate simulation only.Citation: Davies, L., et al. (2013), A single-column model ensemble approach applied to the TWP-ICE experiment,

We theoretically predict and experimentally demonstrate a nonthermal pathway to optically enhance superexchange interaction energies in a material based on exciting ligand-to-metal charge-transfer transitions, which introduces lower-order virtual hopping contributions that are absent in the ground state. We demonstrate this effect in the layered ferromagnetic insulator CrSiTe 3 by exciting Te-to-Cr charge-transfer transitions using ultrashort laser pulses and detecting coherent phonon oscillations that are impulsively generated by superexchange enhancement via magneto-elastic coupling. This mechanism kicks in below the temperature scale where short-range in-plane spin correlations begin to develop and disappears when the excitation energy is tuned away from the charge-transfer resonance, consistent with our predictions.