  It is known that itinerant metamagnetic transitions can be driven by features
in the electronic density of states. We study the signatures of these
transitions in the entropy and specific heat for a variety of different cases,
identifying the key features which differ from naive expectations, such as
enhanced critical fields and non-Fermi liquid temperature dependencies. We
begin with the generic case of a logarithmically divergent density of states,
as caused by a two dimensional van Hove singularity. We then study a specific
model for the bandstructure of Sr3Ru2O7, a material with a well-studied
metamagnetic transition and quantum critical endpoint. We consider how far the
behaviour of the system can be explained by the density of states rather than
quantum fluctuations, and the distinctive features of this mechanism. One of
the characteristic features of Sr3Ru2O7 is an unusual phase with a higher
entropy than its surroundings, we consider how this may arise in the context of
a density of states picture and find that we can reproduce the thermodynamic
behaviour and first-order phase transitions.
