Spin-Lattice Coupling in the Quantum Spin Ice Candidate Tb2Ti2O7 Revealed by THz Spectroscopy

Abstract

In geometrically frustrated magnetism, the very nature of the ground. [...]

Terahertz magneto-optical investigation of quadrupolar spin-lattice effects in magnetically frustrated Tb2Ti2O7

“…These are observable in X-ray diffraction experiments [11] and manifest as giant magnetostriction [12], elastic softening [7], and pressure-induced magnetic ordering [13]. More recently, inelastic neutron scattering [9,14,15] and THz spectroscopy [16] measurements have highlighted the presence of vibronic coupling as a result of symmetry-allowed hybridization between phonons and the Tb 3+ crystal electric field (CF) states both within the ground and first excited doublets. In particular, these couplings involve quadrupolar operators that depend on the phonon mode inducing the local dynamical strains.…”

Vibronic collapse of ordered quadrupolar ice in the pyrochore magnet Tb$_{2+x}$Ti$_{2-x}$O$_{7+y}$

“…The presence of this fine structure, together with the polarization dependence are the signature of vibronic couplings, see Ref. [1,2] for details. Conversely, wave polarization has no effect on C2 spectra: only the central peak is visible and its intensity is independent of the h direction, showing that the effects of vibronic couplings are not visible for this sample and are therefore weaker.…”

“…The wavefunctions for the ground state doublet |ψ 0 ± and the first excited doublet |ψ 1 ± obtained from the diagonalization of the crystal field hamiltonian H cf are given in Table IV. 1). The value in brackets after the name of a wavefunction is its associated eigenenergy (in cm −1 ).…”

“…A wide spectrum of exotic behaviors built upon magnetic dipolar degrees of freedom were already discovered and are still foreseen. Among them, one finds those induced through magnetic frustration such as quantum spin liquids with fractionnal or anyonic excitations to quote but one example [1,2]. Another emblematic geometric frustration-induced state is the classical spin ice, as observed in Ho 2 Ti 2 O 7 [3], belonging to the pyrochlore family R 2 M 2 O 7 where the magnetic rare earth ions R 3+ form a corner sharing tetrahedra network [4].…”

“…P32404-N27). * yann.alexanian@neel.cnrs.fr; Present adress: Institut Laue Langevin, 38 000 Grenoble, France † sophie.debrion@neel.cnrs.fr [1] C. Lacroix, P. Mendels, and F. Mila, eds., Introduction to Frustrated Magnetism: Materials, Experiments, Theory (Springer, Berlin London, 2011).…”