Spin-orbital excitation continuum and anomalous electron-phonon interaction in the Mott insulator LaTiO${}_3$

Abstract

Raman scattering experiments on stoichiometric, Mott-insulating LaTiO${}_3$ over a wide range of excitation energies reveal a broad electronic continuum which is featureless in the paramagnetic state, but develops a gap of $\sim 800$ cm${}^{-1}$ upon cooling below the Néel temperature $T_N=146$ K. In the antiferromagnetic state, the spectral weight below the gap is transferred to well-defined spectral features due to spin and orbital excitations. Low-energy phonons exhibit pronounced Fano anomalies indicative of strong interaction with the electron system for $T>T_N$, but become sharp and symmetric for $T<T_N$. The electronic continuum and the marked renormalization of the phonon lifetime by the onset of magnetic order are highly unusual for Mott insulators and indicate liquid-like correlations between spins and orbitals.

to appear in Phys. Rev. Lett

References in corpus (6)

• Orbital-Spin Structure and Coupling to Lattice in RTiO${}_3$ with R=La,Pr,Nd and Sm
• Phonon anomalies in pure and underdoped R{1-x}K{x}Fe{2}As{2} (R = Ba, Sr) investigated by Raman light scattering
• Determination of the orbital moment and crystal field splitting in LaTiO${}_3$
• Dielectric properties and dynamical conductivity of LaTiO3: From dc to optical frequencies
• Ferromagnetism and Lattice Distortions in the Perovskite YTiO${}_3$
• The fate of orbitons coupled to phonons

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