Electron spin resonance in the spin-1/2 quasi-one-dimensional antiferromagnet with Dzyaloshinskii-Moriya interaction BaCu2Ge2O7 -: art. no. 057203

We have investigated the electron spin resonance (ESR) on single crystals of BaCu2Ge2O7 at temperatures between 300 and 2 K and in a large frequency band, 9.6-134 GHz, in order to test the predictions of a recent theory, proposed by Oshikawa and Affleck (OA) [Phys. Rev. Lett. 82, 5136 (1999)], which describes the ESR in a spin-1/2 Heisenberg chain with the Dzyaloshinskii-Moriya interaction. We find, in particular, that the ESR linewidth, DeltaH, displays a rich temperature behavior. As the temperature decreases from T-max/2approximate to170 to 50 K, DeltaH shows a rapid and linear decrease, DeltaHsimilar toT. At low temperatures, below 50 K, DeltaH acquires a strong dependence on the magnetic field orientation and for Hparallel toc it shows a (h/T)(2) behavior which is due to an induced staggered field h, according to OA's prediction.