NMR as a local magnetic probe and new trends of using it

Orateur : Tanmoy CHAKRABARTY (National Institute of Chemical Physics and Biophysics (NICPB), Tallinn, Estonia)

NMR is a very effective local probe technique to extract the spin susceptibility and the local information from a magnetic system. In a novel magnetic system, local probe technique such as NMR gives the inner picture about the surrounding magnetic environment of the magnetic ion which helps us understanding the subtle behaviors governing the novelty of the corresponding system. Currently I have been exploring the bulk and NMR properties of a novel vanadium-based spin chain system. The magnetic susceptibility of this system shows a broad maximum around 50 K signifying a short-range magnetic order. Heat capacity measurements also reveal similar trends like magnetism. The (MAS-NMR) measurements clearly demonstrate the local magnetic environment of the V4+ (S = 1/2) ions. The spin susceptibility calculated from the shift of the 51V NMR spectra reproduces the behavior observed in magnetic susceptibility and concurs well with the S = 1/2 uniform spin chain model with J = 113(5) K. Prior to the above-mentioned ongoing work, I have also worked on a new experimental trend that has been developed using NMR as a local probe. Here, materials like transition metal ion-doped substrates are used to attain enhancement of NMR signal using dynamic nuclear polarization (DNP) which includes the complete bulk materials, not only the substrates. This can be hugely applied in medical sciences (MRI) to attain enhancement in a rather novel way, which does not include chemical change of the substrate or restrict the effect only within the surface. In this talk I’ll discuss DNP experiments on one such material where one can be used as a potential candidate for developing the new technique using transition metal ion-doped DNP.

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