Research Papers in Physics and Astronomy


Date of this Version

August 2000


Published in the Journal of Magnetism and Magnetic Materials. Available online August 14, 2000. Published in February 1995, Pages 1555-1556.


In the presence of an applied axial magnetic field Ha the uniaxial antiferromagnets FeCl2 and FeBr2 show fluctuating domain-like antiferromagnetic correlations above the phase boundary Tc(Ha). They are detected by SQUID measurements of the low frequency out-of-phase susceptibility gc″ and indicate a field-induced Griffiths phase at temperatures Tc(Ha) < T < TN. In contrast to FeCl2, important additional frustration-induced intraplanar non-critical contributions to χ″ vs. T are found in FeBr2. For external fields above the Tc(Ha) line, Ha > 2.6 MA/m, they are shown to superimpose linearly on the Griffiths contributions. These dominate at Ha = 2.67 MA/m and are unequivocally modeled within the Landau theory of fluctuations near phase transitions by introducing a Lorentzian Tc distribution.

Included in

Physics Commons