  The heat capacity of conduction electrons obtained from the Sommerfeld
expansion is shown to be tunable via the Rashba and Dresselhaus spin-orbit
coupling parameters. Using an AlInSb/InSb/AlInSb as a representative
heterostructure with alterable well and asymmetric barrier regions, the heat
capacity is found to be higher for the spin-down electrons and suffers a
reduction for wider wells. A further lowering is obtained through the
application of an uniaxial strain. Finally, we suggest a method to determine
the spin lifetimes for spins relaxing via the D'yakonov-Perel' mechanism from
experimental estimates of thermodynamic potentials such as the Helmholtz free
energy and the heat capacity.
