Unconventional relaxation in antiferromagnetic CoRh2O4 nanoparticles

Magnetic relaxation in antiferromagnetic CoRh2O4 nanoparticles is investigated at 2 K by cooling the sample from a temperature (70 K) well above the antiferromagnetic ordering temperature at 27 K, following zero-field-cooled (ZFC) and field-cooled (FC) process. In the ZFC process, the sample at 2 K is subsequently followed by magnetic-field ON and OFF sequences, whereas in the FC process the cooling field is made off during measurement of the remanent magnetization as a function of time. The experiments suggest an unconventional relaxation behavior in the system as an effect of competition between surface exchange anisotropy and antiferromagnetic interactions in antiferromagnetic nanoparticles.