From quantum glass to addressable spin clusters in the model magnet LiHoxY1−xF4

This report describes an AC-susceptibility study on $LiHo_xY_{1−x}F_4$. $LiHo_xY_{1−x}F_4 has different phases depending on the concentration x of holmium. Pure$LiHoF_4$is a ferromagnet, at concentrations of$x \approx 0.20$it is a spin glass and at concentrations of$x \approx 0.05$it becomes a spin liquid. The crystal studied here is$LiHo_ {0.04}Y_{0.96}F_4. In this spin liquid phase it shows several interesting properties which differ from ordinary spin glasses. Its spectral width of the imaginary part of the magnetic susceptibility $\chi^{''} narrows with decreasing temperature contrary to spin glasses. We measured the real$\chi^{'}$and the imaginary part$\chi^ {''}$of the magnetic susceptibility at different temperature and over a frequency range of 5 decades. The data are an extension to higher temperature of already existing data and match well with them in the overlapping temperatures. Our data shows well the trend the shift of the peak of the response function for$\chi^{''}$to higher frequencies and the decrease of the peak amplitude with increasing temperature. Also the cut of frequency for$\chi^ {'}$ increases with temperature. This is in agreement with the existing data at lower temperature.