Lattice and magnetic dynamics in perovskite Y1−xLaxTiO3

Abstract

Inelastic neutron scattering combined with the dynamic pair density function (DPDF) analysis were used to investigate the magnetic and lattice dynamics in the orbitally active Y1−xLaxTiO3 as it crosses the antiferromagnetic (AFM) to ferromagnetic (FM) phase boundary. Upon doping, the FM state present in YTiO3 is suppressed on approaching a critical concentration of xc ∼ 0.3 in which TC 0, and is replaced by the AFM phase of LaTiO3. Below xc, magnetic scattering from spin waves is dominant at low energies. At xc with a TC 0, magnetic scattering is also observed and is most likely due to AFM fluctuations. At the same time, local atomic fluctuations extending to 50 meV are observed above and below the magnetic transitions from 0 ≤ x ≤ 1 that show distinct characteristics with x. From Y to La, a clear difference is observed in the phonon density of states (DOS) as a function of doping as well. At x = 0.15 and 0.3, low energy modes involving predominantly the rare-earth ion become suppressed with increasing temperature while in x = 1, strong suppression of phonon modes across a wide range in energy is observed above TN . It is likely that in the Y heavy samples, phonon modes below 20 meV have a stronger influence on the orbital excitations, while in LaTiO3, a strong phonon dependence is observed upon cooling up to TN .

Nature of the ferromagnetic-antiferromagnetic transition in Y$_{1-x}$La$_{x}$TiO$_{3}$

“…Apparent experimental support for this possibility comes from specific heat, magnetic susceptibility (under hydrostatic pressure), and dielectric constant results for single crystals (for x ≤ 0.3), which were interpreted as indicative of a spin-orbital-liquid state between the FM and AFM phases 14 . More recent work focussed on the lattice and magnetic dynamics in polycrystalline samples of Y 1−x La x TiO 3 15 . However, the nature of the evolution of the magnetic ground state is still under debate, and most studies, particularly neutron scattering measurements of single crystals, have been largely restricted to the end compounds YTiO 3 16 and LaTiO 3 17 .…”

Quantum spin Hall and quantum anomalous Hall states in magnetic Ti2Te2O single layer

“…However, if Ti was in Ti 3+ state, then finite local magnetic moment (∼1 μ B ) can be sustained according to Hund's rule. Compounds contain Ti 3+ like YTiO 3 and LaTiO 3 do being magnetic at a low temperature [44] and similarly, we expect that Ti 2 Te 2 O can show magnetism at low temperature. The chessboard AFM Ti 2 Te 2 O single layer is formed by two FM coupled sublattices (figure 1(c)) and each contains one Ti atom and shares the Te and O atoms.…”

Strain-tunable metamagnetic critical endpoint in Mott insulating rare-earth titanates

“…This phenomenology suggests a potential path to realize magnetic QPTs while remaining inside the Mott insulating state via isovalent chemical substitution on the rareearth site [26,27], such as in Sm 1−𝑥 Gd 𝑥 TiO 3 [16] and Y 1−𝑥 La 𝑥 TiO 3 [12,14,17,18]. In principle, there are several possibilities for magnetic QPTs: split transitions from either the AFM or the FM phase to the paramagnetic (PM) phase; split transitions from the AFM or FM phases to a coexistence AFM+FM state; a single first-order AFM to FM transition; or a single second-order AFM to FM transition, which would require fine tuning of parameters.…”