Using element-specific X-ray magnetic circular dichroism (XMCD) technique we have studied different magnetic sublattices in a multiferroic Ho$_{ 0.5}$Nd$_{ 0.5}$Fe$_{ 3}$(BO$_{ 3}$)$_{ 4}$ single crystal. The XMCD measurements at the \emph{ L}$_{ 2,3}$-edges of Ho and Nd, and at the Fe \emph{ K}-edge have been performed at \emph{ T}=2~K under a magnetic field up to 17~T applied along the trigonal \emph{ c}-axis as well as in the basal \emph{ ab}-plane. All three magnetic sublattices are shown to undergo a spin-reorientation transition under magnetic field applied along the \emph{ c}-axis. On the contrary, when magnetic field is applied in the \emph{ ab}-plane only the holmium atoms exhibit a magnetization jump. Thus, the element-specific magnetization curves revealed the Ho sublattice to be much stronger coupled to the Fe one than the Nd sublattice. The results demonstrate that the Ho$^{ 3+}$ subsystem plays even more dominant role in magnetic behavior of Ho$_{ 0.5}$Nd$_{ 0.5}$Fe$_{ 3}$(BO$_{ 3}$)$_{ 4}$ crystal than in pure HoFe$_{ 3}$(BO$_{ 3}$)$_{ 4}$ crystal.
Categories: cond-mat.mtrl-sci