  Using two different configurations of temperature and magnetic field
gradients, we observed that, in a quasi one-dimensional magnetic fluid,
magnetic force either reduces the temperature difference across the sample when
the two gradients are parallel to each other (PL), or increase the temperature
difference when the two gradients are antiparallel (AP), where the single
convection roll in zero field was replaced by two localized flows at the two
ends of the sample cell. This flow structure stops the heat flow of approaching
to thermal equilibrium in the system, causing the temperature at hot side of
the sample cell getting hotter and cold side becoming colder. None of these
phenomena can be described by the existing theories of magnetically-induced
instabilities. The underlying physics for observed results for AP configuration
has been proposed as the mechanism to drive a new type of heat engines that has
much higher efficiency than Carnot engines and has no pollution to the
environment, our results point to the potential feasibility of this proposed
mechanism.
