Specific heat studies on pristine and oxygenated iron tellurides

Specific heat studies carried out on Fe_1.1Te and oxygenated Fe_1.1Te and FeTe₂ in the range 77-300 K exhibit interesting behavior. The specific heat of the pristine sample reveals a well known structural transition associated with antiferromagnetic ordering near 67 K with a small thermal hysteresis of ∼1 K. Contrastingly, the oxygenated samples exhibit a phase transition with a very large thermal hysteresis of ∼100 K. The specific heat transition observed at the 150 and 260 K regions in the oxygenated Fe_1.1Te sample could not be captured by the magnetization measurements indicating that specific heat transitions seen in oxygenated samples may not be of magnetic origin.