Specific heat and magnetic susceptibility of single-crystalline ZnCr2−xAlxSe4 (x=0.15, 0.23)

► Al-substitution does not affect the Cr3+ 3d3 electronic configuration. ► χ″(T) reveals energy loss only in the case of the first-order transition. ► The larger Al-content, the lower value of Hc2 at low temperatures. ► Larger Al-content makes easier the transfer of phonon momentum to the electron gas.