AC magnetic susceptibility measurements is required to study of magnetic phase transitions and spin dynamics with time which is not possible to correctly visualize by DC magnetic measurement. Mainly for spin glass materials (short range magnetic ordered materials), the frequency dependency of transition temperature and of the relaxation time can be calculated.
The a.c. magnetic susceptibility in general is a technique that allows the determination and the separation of different magnetic phases thanks to the characterization of the ‘phase critical temperatures’ and to a quantitative ratio between phases. In more details, a.c. magnetic multi-harmonic susceptibility describes the Fourier series components of the magnetic susceptibility and probes the real and imaginary parts of first and high harmonic susceptibility. It is possible separate information on the linear and non-linear electronic transport processes presents in a material versus temperature, magnetic field and amplitude electronic current by comparison of the first harmonic components with the high harmonic response components. As an example: skin electronic losses are linear processes and only the first harmonic is observed in the susceptibility data. Phase transitions are non-linear processes and the response is not harmonics. In this latter case both the first component and high harmonics susceptibility components are present. Moreover, the frequency of Hac magnetic field sets the time window where the magnetic processes are present and in this way it possible to study the dynamics of the magnetic processes. These measures can determine further the critical temperature also the changing in different magnetic phases of the electronic dynamic, like FM, AFM, SDW or Spin Glass, moreover can be define in the superconductor, the presence of the Superconducing phases, in particular is suitable to investigate the vortex dynamics of superconductors.
The AC susceptibility measurements in are necessary to obtain information on the magnetization dynamics, on the response of the system to the alternating sounding field, and for testing some theoretical models.
AC magnetic susceptibility measurements are required to study of magnetic phase transitions and spin dynamics with time which is not possible to correctly visualize by DC magnetic measurement. Mainly for spin glass materials (short range magnetic ordered materials). These measures can determine further the critical temperature also the changing in different magnetic phases of the electronic dynamic, like FM, AFM, SDW or Spin Glass, moreover can be define in the superconductor, the presence of the Superconducing phases, in particular is suitable to investigate the vortex dynamics of superconductors.
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