Revisiting apparent ideal diamagnetism at ambient conditions in graphene-n-heptane-permalloy systems

TL;DR

This study revisits previous claims of ideal diamagnetism in a graphene-permalloy system, revealing that experimental artifacts, not material properties, likely caused the observed signals.

Contribution

The paper demonstrates that apparent diamagnetism can result from magnetic field inhomogeneities and experimental setup, challenging prior interpretations of similar phenomena.

Findings

Magnetic field redistribution mimics ideal diamagnetism.

Graphene is not responsible for the observed effects.

Experimental geometry influences ultra-low-field magnetic signals.

Abstract

We previously reported apparent ideal diamagnetism at ambient conditions in a graphene-n-heptane-permalloy system. At the same time, the experiments revealed inconsistent behavior, including signal freezing and occasional paramagnetic responses. Further measurements performed without graphene produced similar signals, indicating that graphene is not responsible for the observed effects. The results suggest that magnetic field redistribution caused by inhomogeneities in the permalloy foil and experimental geometry can mimic ideal diamagnetism in sub-milligauss measurements. These findings revise the interpretation of our earlier results and emphasize caution in interpreting ultra-low-field magnetic measurements.