  We present experimental evidence for the simultaneous existence of the
magnons and spin-state transition contributions to the heat capacity in
ferromagnetic (FM) Cr-doped MnTe (Tc~280K), where the magnon heat capacity is
attributed to the observed magnon-bipolar carrier-drag thermopower. The
pristine antiferromagnetic (AFM) MnTe shows only a magnon-induced peak in the
heat capacity near the Neel temperature, TN~307K. However, Cr-doped MnTe shows
a magnon-contributed heat capacity peak at ~293K with an additional peak in the
deep paramagnetic domain near 780K. Temperature-dependent magnetic
susceptibility reveals that Cr-doping initially creates low-spin (LS) states
Mn2+ ions into MnTe near and below TN due to a higher crystal field induced by
Cr ions. Above 400K, LS Mn2+ ions start converting into high-spin (HS) Mn2+
ions. The LS-to-HS transition of Mn2+ leads to an excess entropy and hence
excess heat capacity contribution in the system. Temperature-dependent X-ray
diffraction (XRD) and magnetic field-dependent susceptibility (M-H) confirmed
no presence of any structural changes and magnetic polaron, respectively. Both
XRD and M-H ensure that the peak of the heat capacity in the paramagnetic
domain is originated solely by the spin-state transition. The heat capacity
versus temperature was calculated to explain the contribution of each
component, including the ones due to the phonons, magnons, spin-transition,
Schottky anomaly, and lattice dilation. With the recent advances in
spin-caloritronics extending the spin-based effects from magnetic to
paramagnetic materials, the data from the heat capacity can play a crucial role
to probe the presence of different phenomena such as paramagnon-carrier-drag
and spin-entropy thermopowers.
