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Low energy spin dynamics in trimer spin chain compound Ca 3Cu2Ni(PO4)4: 31P NMR study
M. Ghosh, K. Ghoshray, Amitabha Ghoshray
Published in
2013
Volume: 431

Pages: 19 - 22
Abstract
31P nuclear-magnetic-resonance (NMR) study in the trimer spin chain compound Ca3Cu2Ni(PO4)4 is performed in the presence of different external magnetic fields in the temperature range 4-300 K. The results suggest that the three magnon mediated scattering process which was the dominant contribution to 1/T1 in the pure compound Ca3Cu3(PO4)4, has negligible contribution in Ca3Cu2Ni(PO4) 4, with the two magnon mediated Raman process being dominant. The linear variation of nuclear spin lattice relaxation rate 1/T1T with the magnetic susceptibility $\chi$ indicates that the Q component of magnetic susceptibility $\chi$(Q) is nearly proportional to $\chi$, where Q is the antiferromagnetic wave vector. A change in the slope of 1/T1T with respect to $\chi$ near 15 K suggests a change in the antiferromagnetic spin fluctuation spectrum. Below 15 K, the spin diffusion mechanism governs the 1/T1 process. This could be a signature of the development of short range magnetic correlation or due to the contribution arising from the paramagnetic impurity spins. {\textcopyright} 2013 Elsevier B.V. All rights reserved.