Low temperature magnetic properties of the geometrically frustrated pyrochlores Tb2Ti2O7, Gd2Ti2O7, and Gd2Sn2O7

Static magnetic susceptibility, crystal field and exchange interactions in rare earth titanate pyrochlores

“…The temperature dependence of the single ion susceptibilities χ s and χ s ⊥ was computed according to definitions (9) and (10). The electrostatic, spinorbit, electrostatic configuration and correlated spin-orbit and spin-spin interactions were accounted for in the free ion Hamiltonian H 0 , the corresponding parameters F n , ζ , α, β, γ , T k , P n , M n were taken from the literature [35].…”

“…Parameters of the crystal field Hamiltonian operating in the space of states of the ground 5 I 8 multiplet of the Ho 3+ ions were determined earlier in [28,45]. In the current work, we started from these parameters and obtained a more accurate parameter set (see table 1) from the fitting procedure based on computations of the thermal averages (9) and (10) with the effective Hamiltonian (2) operating in the total space of 1001 states of the 4f 10 configuration. The calculated crystal field energies for several lower multiplets are presented in table 3.…”

“…The temperature dependence of the isotropic susceptibilities of polycrystalline and single crystals of rare earth titanates have been presented in a number of recent publications (R = Sm [3], Eu [4], Gd [5][6][7][8][9][10], Tb [8][9][10][11][12][13][14][15][16], Dy [8,9,[17][18][19][20], Ho [8,9,11,[20][21][22][23], Er [8,11,18,24], Yb [8,11,17,18,25,26]). As a rule, the experimental data were analyzed using the Curie-Weiss law leading to estimations of the effective isotropic exchange coupling constant.…”

Low-Temperature Low-Field Phases of the Pyrochlore Quantum MagnetTb2Ti2O7

“…On the other hand, a muon-spin-rotation (µSR) frequency shift in low magnetic fields, 20 mT and 60 mT, applied along the [110] direction suggests a transition at a lower temperature of about 150 mK, a transition which has not been identified [12]. The static magnetic susceptibility of a zero-field-cooled polycrystalline sample in a 1 mT field shows history dependence suggestive of spin-glass behavior below about 100 mK, with an anomaly at about 70 mK interpreted as the spin-glass transition from the high-temperature phase [9].Numerical diagonalization of a single-tetrahedron fourspin model predicts [24,25] that the zero-field ground state of Tb 2 Ti 2 O 7 is a quantum spin liquid, dubbed a quantum spin ice [24,26], which-with low increasing field along the [111] direction-gradually turns into a partially polarized state akin to the kagome-ice state [27,28] of classical spin-ice magnets. At higher fields, H ≥ 82 mT, it evolves into a "three-in one-out" state, with three spins pointing into and one pointing out of every tetrahedron.…”

A comparison of the local magnetic susceptibility in rare earth pyrochlores

“…The neutron scattering measurements are therefore completely insensitive to the spin dynamics at these low energies. Finally, differences between the field cooled and zero field cooled susceptibility have been reported below 70 mK [28], indicative of spin glass-like behavior. One possible explanation for these results is that Tb 2 Ti 2 O 7 undergoes partial clustering at low temperatures, though the low temperature spin structure is a matter of debate [27,29,30].…”