Dr Tanmoy Chakrabarty, Assistant Professor, Physics, SIAS delivered a presentation at the International Conference on Magnetic Materials and Applications (ICMAGMA2026) organised by NIT Goa and NIT Warangal. The conference was held from 3-5 June 2026 at NIT Goa.
The talk was titled ‘Geometric Frustration and 1D Magnetism Explored By 31P SSNMR IN A S=5/2 Triangular Lattice System’.
Abstract of the talk
Geometric frustration and one-dimensional magnetism boost quantum fluctuations and lead to unusual states of quantum matter. To explore these effects, the team used solid state nuclear magnetic resonance (SSNMR), which is a strong local probe to extract the true spin susceptibility and the spin network of a magnetic system. In this work we studied the magnetic behavior of a well-separated S = 5/2 saw-tooth spin chain compound CaFe2O(PO4)2 (CFPO), which has two different 31P sites in the unit cell (Fig.1). Magnetic susceptibility, heat capacity, and 31P NMR measurements show evidence of strong magnetic frustration (with a frustration parameter ≈ |θCW|/TN) about 70) in CFPO. At high temperatures, χ(T) follows Curie-Weiss behavior (θCW ≈−1073 K), indicating strong AF interactions. At low magnetic fields (0.01 T), χ(T) exhibits an upturn and a distinct bifurcation between the zero-field-cooled (ZFC) and field-cooled (FC) curves near 15.5 K (Fig.2). The bifurcation between the ZFC and FC data is strongly suppressed at 1 T, signalling the weak ferromagnetic nature of the magnetic transition. The major finding of our work came from the 31P NMR measurements, which show a broad maximum near 70 K (Fig.3), reflecting the low-dimensional nature and presence of short-range correlations. We note that such a broad maximum feature is not seen in the bulk χ(T) or heat capacity. Further investigating this broad maximum feature, we conclude that CFPO represents an interesting realization of a frustrated S = 5/2 sawtooth spin-chain.
