Concentration dependence in kinetic arrest of first order magnetic   transition in Ta doped $HfFe_2$
  Magnetic behavior of the pseudo-binary alloy $Hf_{1-x}Ta_xFe_2$ has been studied, for which the zero field ferromagnetic (FM) to antiferromagnetic (AFM) transition temperature is tuned near to T=0 K. These alloys show anomalous thermomagnetic irreversibility at low temperature due to kinetic arrest of the first order AFM-FM transition. All the three studied compositions show re-entrant transition in zero field cooled warming curve and anomalous non-monotonic variation of upper critical field in isothermal magnetization. The region in H-T space, where these features of kinetic arrest manifest themselves, increases with increasing Ta concentration. 
R. Rawat, P. Chaddah, Pallab Bag, P. D. Babu and V. Siruguri
cond-mat.str-el