Pulsed field magnetization measurements in an antiferromagnetic Cu(2+) isosceles triangle

EPR and pulsed field magnetization experiments have been carried out on Na$_{9}$[Cu$_{3}$Na$_{3}$(H$_{2}$O)$_{9}(\alpha $-AsW$_{9}$O$_{33})_{2}$]$\cdot $26 H$_{2}$O, an antiferromagnetic isosceles triangle of Cu(2+) ions, in order to examine the quantum phenomena present in a simple spin-frustrated system. Remarkably, the hysteresis loops are characterized by half magnetization steps and asymmetry between positive and negative fields. The EPR determined energy levels suggest that the mixing of the trimer spin-states via antisymmmetric exchange interactions is a factor which induces quantum tunneling in the system.