The magnetic properties of Na2CuP2O7 were investigated by means of 31P nuclear magnetic resonance (NMR), magnetic susceptibility, and heat capacity measurements. We report the 31P NMR shift, the spin-lattice 1/T1, and spin-spin 1/T2 relaxation-rate data as a function of temperature T. The temperature dependence of the NMR shift K(T) is well described by the S=1/2 square lattice Heisenberg antiferromagnetic (HAF) model with an intraplanar exchange of J/k_B \simeq 18\pm2 K and a hyperfine coupling A = (3533\pm185) Oe/mu_B. The 31P NMR spectrum was found to broaden abruptly below T \sim 10 K signifying some kind of transition. However, no anomaly was noticed in the bulk susceptibility data down to 1.8 K. The heat capacity appears to have a weak maximum around 10 K. With decrease in temperatures, the spin-lattice relaxation rate 1/T1 decreases monotonically and appears to agree well with the high temperature series expansion expression for a S = 1/2 2D square lattice.
@article{arxiv.cond-mat/0602010,
title = {31P NMR study of Na2CuP2O7: a S=1/2 two-dimensional Heisenberg antiferromagnetic system},
author = {R. Nath and A. V. Mahajan and N. Buettgen and C. Kegler and J. Hemberger and A. Loidl},
journal= {arXiv preprint arXiv:cond-mat/0602010},
year = {2016}
}
Comments
12 pages, 8 figures, submitted to J. Phys.: Cond. Mat