Magnetic crossover and complex excitation spectrum of the ferromagnetic/antiferromagnetic spin-1/2 chain system alpha-TeVO4

摘要

We report magnetic susceptibility, specific heat, and Raman scatteringinvestigations of alpha-TeVO4 containing V-O edge-sharing chains. These chainspromote a system of ferromagnetic/antiferromagnetic spin-1/2 Heisenbergalternating exchange chains with pronounced spin frustration. The magneticsusceptibility and Raman scattering evidence a crossover at T* = 85 K withdifferent slopes of the reciprocal susceptibility and a magnetic phasetransition into a long-range-ordered state at Tc = 16 K. From Raman scatteringdata a strong mutual coupling between lattice and magnetic degrees of freedomis deduced. A comparison to model calculations and prior Raman scattering onother chain systems yield a plausible interpretation of the microscopicmechanism for the crossover behavior.