Comment on `Intrinsic tunnelling spectroscopy of Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$: The junction-size dependence of self-heating'[Phys.Rev.B 73, 224501 (2006)]

The recent PRB 73, 224501 (2006) henceforth referred as Ref.\cite{0} asserts that self-heating decreases with sample area reduction and claims to identify the intrinsic cause of ITS in submicrometre `mesa'. I will show that this assertion lacks substantiation. I will further demonstrate that one and the same $R(T)$ and the parameter-free Newton's Law of Cooling describe quantitatively a rich variety of ITS behaviours taken by Ref.\cite{0} above and below $T_c$ at bath temperatures spanned over 150K. Thus this finding presents strong evidence in favour of heating as the cause of the `intrinsic tunnelling spectra' (ITS) promoted by Ref.\cite{0}.