  We present a computational study of isochoric heating in multi-layered
targets at ultra-high intensity laser irradiation (approx. 10**20 W/cm**2).
Previous studies have shown enhanced ion heating at interfaces, but at the cost
of large temperature gradients. Here, we study multi-layered targets to spread
this enhanced interface heating to the entirety of the target and find heating
parameters at which the temperature distribution is more homogeneous than at a
single interface while still exceeding the mean temperature of a non-layered
target. Further, we identify a pressure oscillation that causes the layers to
alternate between expanding and being compressed with non beneficial effect on
the heating. Based on that, we derive an analytical model estimating the
oscillation period to find target conditions that optimize heating and
temperature homogeneity. This model can also be used to infer the plasma
temperature from the oscillation period which can be measured e.g. by XFEL
probing.
