Publications

@article{Flinn2024-yd,

title = {Sensing the spin state of room-temperature switchable  cyanometallate frameworks with nitrogen-vacancy centers in  nanodiamonds},

author = {Bradley T Flinn and Graham A Rance and William J Cull and Ian Cardillo-Zallo and Jem Pitcairn and Matthew J Cliffe and Michael W Fay and Ashley J Tyler and Benjamin L Weare and Craig T Stoppiello and E Stephen Davies and Melissa L Mather and Andrei N Khlobystov},

doi = {10.1021/acsnano.3c11820},

year  = {2024},

date = {2024-03-01},

urldate = {2024-03-01},

journal = {ACS Nano},

volume = {18},

number = {9},

pages = {7148\textendash7160},

publisher = {American Chemical Society (ACS)},

abstract = {Room-temperature magnetically switchable materials play a vital 

 role in current and upcoming quantum technologies, such as 

 spintronics, molecular switches, and data storage devices. The 

 increasing miniaturization of device architectures produces a 

 need to develop analytical tools capable of precisely probing 

 spin information at the single-particle level. In this work, we 

 demonstrate a methodology using negatively charged nitrogen 

 vacancies (NV-) in fluorescent nanodiamond (FND) particles to 

 probe the magnetic switching of a spin crossover (SCO) 

 metal-organic framework (MOF), 

 [Fe(1,6-naphthyridine)2(Ag(CN)2)2] material (1), and a 

 single-molecule photomagnet [X(18-crown-6)(H2O)3]Fe(CN)6·2H2O, where X = Eu and Dy (materials 2a and 2b, respectively), in 

 response to heat, light, and electron beam exposure. We employ 

 correlative light-electron microscopy using transmission 

 electron microscopy (TEM) finder grids to accurately image and 

 sense spin-spin interacting particles down to the 

 single-particle level. We used surface-sensitive optically 

 detected magnetic resonance (ODMR) and magnetic modulation (MM) 

 of FND photoluminescence (PL) to sense spins to a distance of 

 ca. 10-30 nm. We show that ODMR and MM sensing was not sensitive 

 to the temperature-induced SCO of FeII in 1 as formation of 

 paramagnetic FeIII through surface oxidation (detected by X-ray 

 photoelectron spectroscopy) on heating obscured the signal of 

 bulk SCO switching. We found that proximal FNDs could 

 effectively sense the chemical transformations induced by the 

 200 keV electron beam in 1, namely, AgI $rightarrow$ Ag0 and 

 FeII $rightarrow$ FeIII. However, transformations induced by 

 the electron beam are irreversible as they substantially disrupt 

 the structure of MOF particles. Finally, we demonstrate NV- 

 sensing of reversible photomagnetic switching, FeIII + 

 (18-crown-6) ⇆ FeII + (18-crown-6)+ •, triggered in 2a and 2b by 

 405 nm light. The photoredox process of 2a and 2b proved to be 

 the best candidate for room-temperature single-particle magnetic 

 switching utilizing FNDs as a sensor, which could have 

 applications into next-generation quantum technologies.},

keywords = {metal−organic framework, nanodiamond, Nitrogen-vacancy sensing, photomagnetism, spin-crossover, transmission electron microscopy},

pubstate = {published},

tppubtype = {article}

}