Investigations of scaling and dynamics in the kagome ice phase of Ho2Ti2O7

Applying a medium strength field along the [111] direction of the geometrically frustrated spin ices Ho2Ti2O7 and Dy2Ti2O7 results in a magnetization plateau called kagome ice. Competition between the ice rules and applied field separates the pyrochlore structure into alternating kagome and triangular planes, creating a quasi-two dimensional analog of spin ice with distinct spin correlations [1]. The concentration of spin flip excitations (recontextualized as magnetic monopole quasiparticles [2]) experiences various crossovers with increased field and temperature visible as critical inflections in the magnetization, specific heat [3] and susceptibility [4]. As the energy of spin flip excitations in the kagome plane changes with field, the mobility of monopole quasiparticles is constrained further from their spin ice counterparts. Using diffuse neutron scattering and high frequency susceptibility measurements on a Ho2Ti2O7 single crystal, alongside Monte Carlo simulations, we have observed and characterized signals of scaling and crossovers attributed to changing monopole density above the critical point.

[1] Fennell et al., Nat. Phys. 3, 8 (2007)
[2] Castelnovo et al., Nature 451, (2008)
[3] Hiroi et al., JPSJ 72, (2003)
[4] Bovo et al., Nat. Com. 4, (2013)