Simulation of electron holography of pyrochlore spin ice

A major topic in frustrated magnetism is emergent magnetic monopoles in spin ice [1]. These low-energy excitations are effective classical analogues of Dirac monopoles and have only been seen indirectly thus far [2]. Electron holography could allow for direct observations due to its high sensitivity to magnetic fields. Electron holography has achieved 3D spatial imaging of spin phenomena with nanometer resolution [3]. This makes the technique uniquely suited for directly imaging spin ice monopoles.
I have developed computational methods to predict how an electron wave would propagate through the spin ice’s magnetic structure. The dipole arrangement of pyrochlore spin ice thin films was generated with the help of Monte Carlo simulation [4]. From there I calculate the magnetic vector potential around the spin ice, and its resulting effect on electron phase. These simulated results enable us to show for the first time what a monopole would look like if imaged using electron holography, and what it would take to achieve in experiment.

[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).