Photoinduced Magneto-Structural Interplay at the Interface of Core@Shell Nanoparticles*

Core@shell heterostructures of Prussian blue analogues (PBAs), namely Rb_xCo[Fe(CN)₆]_y@K_aNi[Cr(CN)₆]_b, show a photoinduced decrease in magnetization of the non-photoactive K_aNi[Cr(CN)₆]_b shell when irradiated with white light below Tc = 70 K [1,2].  This decrease is magnetomechanical in origin, where the photoinduced volume changes of the core and the resulting change of strain in the shell reduce the shell magnetization.  An initial model provided an estimate of the strain depth in the shell [2], and now this model has been extended to comprehensively describe data from three new sets of core@shell heterostructures (one set = one RbCoFe PBA core and three different KNiCr PBA shells).  Increasing the core size from ≈ 125 nm to ≈ 575 nm modifies the shell strain depth from ≈ 45 nm to ≈ 110 nm.  The assumption of a rigid core fails, and PXRD data show a quantitative model for the strain depth must also account for the effect of the strain induced in the core [2,3].  Proposed SANS studies of the shell magnetization will be described.

[1] M.F. Dumont et al., Inorg. Chem. 50 (2011) 4295.

[2] A.C. Felts et al., J. Phys. Chem. C 120 (2016) 5420.

[3] A.C. Felts et al., J. Am. Chem. Soc. 140 (2018) 5814.