Tunable Spin Correlated‐Plasmons Ranging from Infrared to Ultraviolet in Pr_0.6Sr_0.4Co_1−xMn_xO₃

Abstract

Herein, new spin correlated‐plasmons in Pr0.6Sr0.4Co1−xMnxO3 (x = 0–0.4) that are tunable and stable at room temperature are demonstrated. Using advanced spectroscopic techniques, the charge, spin, and orbital interaction that triggers the spin correlated‐plasmons in spin‐polarized Co4+, O2−, and Mn4+ is identified. As a function of x, Co4+ systematically changes the spin state of the spin correlated‐plasmons (from high, intermediate, to low spin), which also sequentially transforms the metallic cobaltite into a Mott insulator. Spin correlated‐plasmons in the IR range, being excited from Co4+, tend to dominate in the metallic phase of the cobaltites, whereas Mn4+ and O2− are the primary source for the spin correlated‐plasmons in the UV–vis ranges in the insulating phase.

Tunable Collective Excitations in Epitaxial Perovskite Nickelates

“…The multifrequency characteristic of LSNO enhances the optical modulation flexibility, adapting to diverse wavelength ranges. Aligned with correlated plasmons observed in copper oxide-based high-temperature superconductors, , LNO exhibits a unique feature: simultaneous excitation of conventional and correlated plasmons in the same position of LF spectraan unprecedented phenomenon. This supports the efficient coupling of correlated plasmons to free-space photons, enhancing metallic plasmon excitation.…”

“…Previous studies have shown that the existence of both peaks in ε 2 and LF spectra suggests a strong coupling between the optical and plasmonic excitations of LNO and is indicative of correlated plasmons. 8,41 This implies that peak B* is the correlated plasmon excitation peak in LNO. Similarly, in LSNO (0.25), peak B* (∼3.34 eV) and peak B′ (∼3.36 eV) were observed in the same position in the ε 2 spectrum and LF spectrum, suggesting the presence of correlated plasmons as well.…”

Coupled harmonic oscillator models for correlated plasmons in one-dimensional and quasi-one-dimensional systems

“…This has prompted recent experimental studies to find correlated plasmons in novel materials systems like Mott-insulating cuprates [26] and topological insulators [27,28]. Other experimental work has also focused on finding other plasmons arising from the interplay of short-range and long-range interactions in materials, like quasilocal plasmons [29,30] and spincorrelated plasmons [31,32].…”