Magnetic Switching of Second-Harmonic Generation from Single Cerium-Based Coordination Polymer Microcrystals

Conventional access and modulation of second-harmonic
generation
(SHG) require precise control of crystal orientation, which faces
great mechanical challenges in the case of micro/nanocrystals. Here,
we demonstrate the magnetic-field-tunable SHG performance of lanthanide
coordination polymer (Ce-BTC CP) microcrystals through field-aligned
orientations. The coordination of Ce ions and organic ligands constructs
a noncentrosymmetric structure, which not only contributes to a favorable
powder SHG efficiency 3.2 times larger than that of the benchmark
KH2PO4 (KDP) but also endows the microcrystals
with strong magnetic anisotropy. The SHG efficiency (∼0 to
10 × KDP) depends on the orientation of the crystallographic c-axis, whereas magnetic anisotropy always aligns the c-axis with the magnetic field at a specific angle. Accordingly,
the SHG can be magnetically switched by field-induced alignments.
The adsorption of dyes by Ce-BTC CPs further facilitates the magnetic
switching of multicolor fluorescence that can be excited by the SHG.
Our work provides a new pathway for achieving SHG modulation at the
microscopic level.