Strongly correlated electron systems in high magnetic fields IV

The observed sensitivity of strongly correlated metals to laboratory magnetic fields of the order of 5-50 Tesla presents a significant theoretical puzzle and challenge. There have been very few calculations on lattice models such as the Hubbard model in a magnetic field. The few calculations that have been done only see very small perturbative effects on the scale of laboratory fields. They require huge magnetic fields of the order of a thousand Tesla for any significant effect, such as a change in ground state.

In terms of coupling of the magnetic field to the orbital degrees of freedom, most studies have been on ladder models (e.g. this PRB), at zero temperature, and only see significant effects at extremely high fields, of the order of thousands of Tesla, when there is a quantum of magnetic flux through a single lattice plaquette. The smaller field scale of the upper critical field for superconductivity corresponds to the longer length scale of a superconducting coherence length. This longer scale may only be accessible on sufficiently large square lattices.