Electrical and magnetic properties of hafnium disulfide intercalated with iron atoms

Simultaneous study of the dependences of the structural parameters, electrical, and magnetic properties of hafnium disulfide intercalated iron atoms in the dependence on the intercalate concentration and temperature has been performed for the first time. The temperature dependences of the electrical resistance are shown to exhibit the activation character with the activation energies characteristic of impurity conduction. The effective magnetic moments of iron ions in Fe$_ x$ HfS$_2$ is found to be significantly lesser than the values of free iron ions and to decrease as the iron content increases. The character of the temperature dependences of the effective magnetic moments and negative values of the paramagnetic Curie temperatures indicate possible interactions of the antiferromagnetic type between intercalated atoms. However, the dependences of the magnetization on field for Fe$_{0.33}$HfS$_{2}$ and Fe$_{0.5}$HfS$_{2}$ obtained at $T$ = 2 K demonstrate the hysteresis phenomenon characteristic of the ferromagnetic state. The results are discussed assuming the existence of hybridization 3 $d$ electron states of intercalated iron atoms with the electronic states of HfS$_2$ matrices and the competition of various exchange interaction.