Study of possible quantum Dirac string in Nd2Zr2O7 in the (001) fields

Magnetic pyrochlore compounds display various fascinating physical phenomena due to geometrical frustration on the network of corner-sharing tetrahedra in the crystal structure. The classical spin ice state with macroscopic degeneracy and monopole-like excitations connected by Dirac strings are probably the most striking which was observed in (Ho/Dy)2Ti2O7. Classical spin ice (CSI) can be melted by quantum fluctuations introduced by terms transverse to the Ising axes in the spin Hamiltonian [3]. A magnetic field along the (001) direction polarized the spin ice state and aligns the Dirac string along the field direction. Here we propose to measure the excitations of the polarized quantum spin ice state in Nd2Zr2O7 in (001) field which could be propagating quantum Dirac strings.