Unveiling Spin Transition at Single-Particle Level in Levitating Spin Crossover Nanoparticles

[EN] The ability to control and understand phase transitions of individual nanoscale building blocks is key to advancing the next generation of low-power reconfigurable nanophotonic devices. To address this critical challenge, molecular nanoparticles (NPs) exhibiting spin crossover (SCO) phenomenon...

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Bibliographic Details
Authors: Pinilla-Cienfuegos, Elena|||0000-0002-3734-0821, Lucas, Torres-Cavanillas, Ramon, Echavarria, J. Ignacio, Regueiro, Alejandro, Coronado, Eugenio, Hernandez-Rueda, Javier
Format: article
Publication Date:2026
Country:España
Institution:Universitat Politècnica de València (UPV)
Repository:RiuNet. Repositorio Institucional de la Universitat Politécnica de Valéncia
Language:English
OAI Identifier:oai:dnet:riunet______::765ccf3819127ae337566a222e8cd700
Online Access:https://riunet.upv.es/handle/10251/233545
Access Level:Open access
Keyword:Spin crossover
Molecular materials
Quadrupoletrap
Multispectral scattering microscopy
Laser-inducedspin transition
Single-nanoparticle sensing
Single-particlephotonics
Description
Summary:[EN] The ability to control and understand phase transitions of individual nanoscale building blocks is key to advancing the next generation of low-power reconfigurable nanophotonic devices. To address this critical challenge, molecular nanoparticles (NPs) exhibiting spin crossover (SCO) phenomenon are trapped by coupling a quadrupole Paul trap to a multispectral polarization-resolved scattering microscope. This contact-free platform simultaneously confines, optically excites, and monitors the spin transition in Fe(II)-triazole NPs in a pressure-tunable environment, eliminating substrate artifacts. Thus, we demonstrate light-driven manipulation of the spin transition in levitating NPs, enabled by laser heating and free of substrate-induced effects. Using the robust spin bistability near room temperature of our SCO system, we quantify reversible optovolumetric changes of up to 10%, revealing precise switching thresholds at the single-particle level. Independent pressure modulation produces a comparable volume increase, confirming mechanical control over the same bistable transition. These results constitute full real-time control and readout of spin states in levitating SCO NPs, with operating conditions compatible with ultralow-power optical switching, data storage, and nanoscale sensing.