Lost and found: The missing diabolical points in the Fe$_8$ molecular magnet

TL;DR

This paper clarifies the existence and location of previously missing diabolical points in the Fe$_8$ molecular magnet's tunneling spectrum, emphasizing their displacement rather than elimination due to anisotropy effects.

Contribution

It demonstrates that missing diabolical points are displaced in magnetic field space, not eliminated, and provides a numerical method to locate them via Berry curvature lines.

Findings

Missing diabolical points are displaced along the medium anisotropy direction.

Numerical location of these points is achieved through Berry curvature analysis.

Experimental search for these points is important for understanding the system.

Abstract

Certain diabolical points in the tunneling spectrum of the single-molecule magnet Fe$_8$ were previously believed to be have been eliminated as a result of a weak fourth-order anisotropy. As shown by Bruno, this is not so, and the points are only displaced in the magnetic field space along the medium anisotropy direction. The previously missing points are numerically located by following the lines of the Berry curvature. The importance of an experimental search for these rediscovered points is discussed.