Spin-liquid-like state in pure and Mn-doped TbInO3 with a nearly triangular lattice

Abstract

Inelastic neutron scattering studies in single crystals of TbInO3 and TbIn0.95Mn0.05O3 with nearly-triangular antiferromagnetic lattice are reported. At low energies, a broad and apparently gapless continuum of magnetic excitations, located at the triangular lattice (TL) Brillouin zone boundary, is observed. The data are well described by the uncorrelated nearest-neighbor valence bonds model. At higher energies, a broad excitation branch dispersing from the TL zone boundary is observed. No signs of static magnetic order are found down to the temperatures two orders of magnitude smaller than the effective interaction energy. The fluctuating magnetic moment exceeds two thirds of the Tb 3+ free-ion value and is confined to the TL plane. These observations are consistent with a TL-based spin liquid state in TbInO3.

Crystal-field excitations and vibronic modes in triangular-lattice spin-liquid candidate TbInO$_3$

“…On the contrary, the observations of another INS study by M.G. Kim et al are consistent with a SL state based on triangular lattice [8]. Such a scenario implies that the CF ground states of Tb1 and Tb2 are the same, and the SL state might have a continuous symmetry.…”

“…The distortion from ideal triangular lattice is weak because the buckling of Tb1 is only 0.38 Å, around one tenth of the in-plane Tb2-Tb2 distance (3.65 Å) [7]. The fluctuating magnetic moment is shown to be confined to the triangular-lattice plane [8]. Magnetic susceptibility of polycrystalline samples obeys Curie-Weiss law above 10 K, with the Weiss temperature being -17.2 K; how- * mye@physics.rutgers.edu † girsh@physics.rutgers.edu ever, no magnetic ordering or spin freezing occurs down to 0.1 K [7], indicating strong magnetic frustration.…”

“…In this section we present the inter-multiplet excitations within the 7 F term of Tb 3+ ions. The electronic configuration of Tb 3+ ion is 4f 8 . According to Hund's rules, the 7 F term has the lowest energy.…”

“…By now the low-energy CF level scheme is established [Table III], and we can relate our results to the two excitation branches measured in the INS study [8]: their gapless excitation extending to 1.4 meV likely corresponds to the Raman-measured 0.8 meV singlet with 0.5 meV width; their broad excitation between 1.6 and 3.0 meV matches well the Raman-measured 2.5 meV singlet with 0.7 meV width. Low-temperature CF excitations in insulators are expected to be sharp [23].…”

“…It has been recently proposed that ferroelectric insulator TbInO 3 could harbor a 2D spin-liquid ground state [7][8][9]. In the ferroelectric phase this material has a hexagonal structure [10] (space group P 6 3 cm, No.…”