Proposal for Observing Magnetic Monopoles in Spin Ice via Electron Holography*

While the magnetic monopole proposed by Pierre Curie and Paul Dirac have remained elusive, emergent monopoles of the H field have been shown to exist in spin ice [1]. Signatures of these monopoles have been indirect so far, leaving their direct observation an open challenge since their discovery [2]. One such technique that could realize this direct observation is electron holography, due to the electron's sensitivity to magnetic fields via the Aharonov-Bohm effect [3]. We explore the possibility of imaging monopoles via electron holography through experimental measurements of monopole and spin ice analogs, and computational simulation of how monopoles would appear in a pyrochlore spin ice thin film [4]. These results suggest that imaging the dynamics of monopoles in thin films of spin ice through electron holography is a realistic possibility.

[1] Castelnovo, C., et al. Nat 451(7174), 42–45 jan (2008).
[2] Castelnovo, C., et al. Annu Rev Conden Ma P 3(1), 35–55 (2012).
[3] Park, H. S., et al. Nat Nano 9(5), 337–342 may (2014).
[4] Jaubert, L., et al. Phys Rev Lett 118(20), 207206 may (2017).