Journal ArticleUltrafast modification of coherent phonons during the photoinduced insulator-to-metal phase transition in neodymium nickelateDogadov, Oleg (ORCID:0009000121585138); Pan, Grace A (ORCID:0000000245121215); Villa, Andrea (ORCID:0000000171476987); Ferenc_Segedin, Dan (ORCID:0000000171628100); Marsik, Premysl (ORCID:0000000197598325); Brooks, Charles M (ORCID:0000000190877321); Paik, Hanjong (ORCID:0000000283634679); Song, Qi (ORCID:0000000212544131); Russo, Valeria; Casari, Carlo S; Mundy, Julia A (ORCID:0000000184540124); Cerullo, Giulio (ORCID:0000000295342702); Dal_Conte, Stefano (ORCID:0000000185823185)<p>The interplay between electronic and lattice degrees of freedom in the insulator-to-metal transition (IMT) in rare-earth nickelates is a long-standing question. In the present work, broadband ultrafast transient reflectivity (TR) spectroscopy is applied to study the photoinduced IMT in<math><msub><mi>NdNiO</mi><mn>3</mn></msub></math>. Both coherent and incoherent terms of the TR signal show discontinuous behavior around the same pump fluence value. A drastic drop in the sample reflectivity appearing at<math><mrow><mo>∼</mo><mn>100</mn></mrow></math>fs timescale in the high excitation density regime indicates the closing of the gap across the IMT. In this regime, coherent phonons associated with the low-temperature crystal phase are not observed even at early time delays, indicating an ultrafast transformation of the lattice potential. A detailed analysis of the coherent phonons indicates a strong coupling between some phonon modes, electronic excitations, and possibly the magnetic order. In this study, we provide insights into the ultrafast dynamics of rare-earth nickelates.</p>APS2026-01-0110671045Physical Review B11312469-9950https://doi.org/10.1103/yg97-vfmn2039380National Science Foundation