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

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 when irradiated with white light below T_c = 70 K of the non-photoactive K_aNi[Cr(CN)₆]_b shell [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. A simple model provides an estimate of the strain depth in the shell, but only one core size was studied [2]. The data from three new sets of core@shell heterostructures provide evidence of the core size dependence on the shell strain depth (one set = one RbCoFe PBA core and three KNiCr PBA shells). Increasing the core size from 328 ± 29 nm to 575 ± 113 nm modifies the shell strain depth from ≈ 50 nm to > 90 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]. SANS studies of the strain-sensitivity of the shell magnetization are being developed and potential samples are presented.
[1] M.F. Dumont et al., Inorg. Chem. 50 (2011) 4295.
[2] A.C. Felts et al., J. Phys. Chem. C 120 (2016) 5420.