High field ESR measurements of quantum antiferromagnetic chain substances BaCu2(Si1−xGex)2O7 Original Research Article

High field ESR measurements of S=1/2 one-dimensional quantum antiferromagnetic (AF) system BaCu2(Si1−xGex)2O7 have been performed using powder samples and pulsed magnetic field. High field electron paramagnetic resonance at 352 GHz and 86 K enabled us to determine the x dependence of g-values even when we used the powder samples. The x dependence will be discussed in connection with the crystal field. Moreover, antiferromagnetic resonances of x=0 and x=1 samples below TN were observed and their frequency–field relations suggest the existence of Dzyaloshinsky–Moriya interaction.