Field-induced quantum spin-1/2 chains and disorder in Nd2Zr2O7

We present a single-crystal diffuse neutron scattering study on the quantum spin ice candidate Nd₂Zr₂O₇ pyrochlore in magnetic fields along the (110 ) direction. Two-dimensional scattering sheets perpendicular to the (1 1 ¯0 ) direction were observed, evidencing field-induced one-dimensional correlations and disorder. The pyrochlore lattice is completely separated into orthogonal sets of chains, which is in strong contrast to classical spin ice and surprising for an "all-in-all-out" (AIAO) ordered magnet with a non-Ising Hamiltonian. Our mean-field and Monte Carlo simulations reveal that the (110 ) field induces a transition from the AIAO order to a "two-in-two-out" disordered state with interactions between the two sets of chains canceled out, resulting in disorder and quantum spin-1/2 X Y Z chains.