LOW DIMENSIONAL SPIN SYSTEMS IN HIGH MAGNETIC FIELDS: SPIN-PHONON INTERACTION

摘要

We discuss ESR- and ultrasonic experiments for quasi- one and twodimensional spin-systems. We found several effects for (VO)_2P_2O_7 and SrCu_2(BO_3)_2. With ESR, we determined the magnetic excitation spectrum and with ultrasonic measurements wo wore able to follow these excitations to lowest frequencies. The spin-phonon interaction is of the exchange-striction type and with ultrasonic experiments we are able to determine the strain dependence of the magnetic coupling constant.