Magnetic-Field Induced Slow Relaxation in the Ising-Like Quasi-One-Dimensional Ferromagnet KEr(MoO_4)_2

Abstract

We present the study of spin dynamics of KEr(MoO4)2 in the magnetic field applied along the hard axis c. The temperature dependence of AC susceptibility in zero magnetic field studied at frequencies f = 10, 100, and 1000 Hz indicated the absence of relaxation in the temperature range from 2 to 20 K. Application of magnetic field induced a slow magnetic relaxation, which was investigated in detail in the field 0.5 T. The highest intensity of the relaxation process, reflected by the values of imaginary susceptibility was observed at 2 K. With increasing temperature, the relaxation process is weaker and vanishes completely above 3.5 K. Corresponding Cole-Cole diagrams were constructed and analyzed within a single relaxation process which can be associated with a direct relaxation process with a bottleneck effect, τ ≈ 1/T b , and b = 1.4. The slow relaxation at 2 K intensifies with increasing magnetic field at least up to 1 T.