  The effects of bath-induced dissipation on the orbital diamagnetism of band
electrons are studied using the gauge-invariant Keldysh Green function
formalism. Orbital diamagnetism is a quantum phenomenon that arises from the
coherent cyclotron motion of the electrons. The system-bath entanglement is
expected to disrupt this coherent electronic motion and quench orbital
diamagnetism. Here, we show that a suitably-tailored bath can lead to an
enhancement of the orbital diamagnetic susceptibility of a multi-band electron
system and can even convert a paramagnetic response into a diamagnetic one as
the system-bath coupling is increased. Furthermore, we demonstrate how van Hove
singularities in the bath density of states can be exploited to generate a
giant enhancement of the orbital magnetic susceptibility. Our work opens doors
to the possibility of controlling the orbital magnetic response of band
electron systems through bath engineering.
