Raman scattering of magnetic excitations of independent antiferromagnetic spin chains in (VO)(2)P2O7

Raman scattering experiments on (VO)(2)P2O7 single crystals revealed a shou lder at approximate to 90 cm(-1) due to magnetic light scattering on differ ent spin chains in addition to the one known at approximate to 45 cm(-1). O ur experimental data correspond to spin gaps of approximate to 64.7 and 32. 4 K, respectively, in good correspondence with the results obtained by neut ron scattering experiments giving independent evidence for the coexistence of double antiferromagnetic (AF) alternating Heisenberg chains in (VO)(2)P2 O7. Our results resolve a discrepancy in the literature between light scatt ering on the one hand and neutron scattering, susceptibility and NMR experi ments on the other hand.