Distinguishing dipolar and octupolar quantum spin ices using contrasting magnetostriction signatures

Sleuthing out exotic quantum spin liquidity in the pyrochlore magnet Ce$_2$Zr$_2$O$_7$

“…The fact that neither magnetic order nor spin glassiness is seen in cerium pyrochlores Ce 2 Zr 2 O 7 and Ce 2 Sn 2 O 7 24,27 may be taken as an additional, albeit indirect, evidence of the robustness of the underlying octupolar spin liquid. While the possibility of such a quantum spin liquid has been entertained in seminal theoretical studies before 3,10 , our present work firmly identifies Ce 2 Zr 2 O 7 as a very promising host for the π-flux octupolar quantum spin ice phase. The present study also underscores the importance of carefully fitting multiple experiments, including specific heat and magnetization, in addition to the INS spectra, to determine the effective model Hamiltonian, which otherwise may be plagued with uncertainties affecting the searches and identification of QSLs 28,29 .…”

Ground-state phase diagram of dipolar-octupolar pyrochlores

“…Note added. Recently, the author became aware of a recent paper by Patri et al [61], which also presents calculations of the ground-state phase diagram of DO pyrochlores.…”

The case for a U(1)$_π$ Quantum Spin Liquid Ground State in the Dipole-Octupole Pyrochlore Ce$_2$Zr$_2$O$_7$

“…This latter case is known to describe the CEF Kramer's ground state of 4f 1 Ce 3+ in Ce 2 Zr 2 O 7 [7,8], a dipole-octupole (DO) ground state doublet, and also that of its sister pyrochlore, Ce 2 Sn 2 O 7 [9]. Such DO doublets decorating pyrochlore lattices are theoretically known to allow for at least 6 distinct quantum disordered and ordered ground states, with three in each of the dipole and octupole sectors [10][11][12]. Recent neutron scattering measurements on single crystal Ce 2 Zr 2 O 7 have uncovered a signal that strongly resembles predictions for FIG.…”

“…For Ce 3+ DO doublets decorating a pyrochlore lattice, the general form of the nearest-neighbour exchange Hamiltonian can be reduced to an XYZ model with only three independent exchange parameters (J x, J ỹ , J z ) in zero magnetic field [5,6]. Theory has predicted the groundstate phase diagram for such an XYZ Hamiltonian, uncovering both quantum spin liquid (QSL) as well as ordered ground states [10,11]. Each of these can have either dipolar or octupolar nature -a QSL phase has octupolar nature if…”