Terahertz ionic Kerr effect: Two-phonon contribution to the nonlinear optical response in insulators

Basini, M.; Udina, M.; Pancaldi, M.; Unikandanunni, V.; Bonetti, S.; Benfatto, L.

doi:10.1103/physrevb.109.024309

Cited by 2 publications

(4 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In ref. 23 it was shown that the EKE response is given by where E x and E y are the components of the pump pulse along generic x and y orthogonal directions, ϑ is the angle that x and y form with respect to the main crystallographic axes ( i and j ) and , as are the only two independent tensor components of the χ (3) tensor in cubic STO from ref. 58 .…”

Section: Methodsmentioning

confidence: 99%

“…Besides the EKE, it has been shown that an additional contribution, IKE, associated with the nonlinear excitation of the infrared-active soft phonon mode, is present 23 . The IKE response can be effectively modelled by replacing the E x and E y components in ∆ Γ e with a convolution between the pump and the single- or two-phonon propagators to account for the intermediate second-order excitation of the soft mode.…”

Section: Methodsmentioning

confidence: 99%

“…Two peaks of comparable amplitudes are, on the other hand, expected when accounting for the electronic nonlinear response associated with χ (3) , namely the third-order susceptibility tensor 22 . We present a detailed combined theoretical and experimental study on this aspect in a separate work 23 , which accounts for the symmetry properties of the crystal and for the specific spectral features of the pump pulse. We anticipate here that the theory predicts an effect proportional to the product of the E x and E y components of the incident terahertz field, as we show in Fig.…”

Section: Mainmentioning

confidence: 99%

“…4a,b in the time and, respectively, frequency domains. We also show the calculated nonlinear optical response of the material due to the Kerr effect 23 , which comprises an electronic (EKE) and a ionic (IKE) contribution, as described in the Methods . Finally, the expected polarization rotation resulting from the sum of the two effects is shown in the same figure.…”

Section: Mainmentioning

confidence: 99%

See 3 more Smart Citations

Terahertz electric-field-driven dynamical multiferroicity in SrTiO3

Basini,

Pancaldi,

Wehinger

et al. 2024

Nature

Self Cite

View full text Add to dashboard Cite

The emergence of collective order in matter is among the most fundamental and intriguing phenomena in physics. In recent years, the dynamical control and creation of novel ordered states of matter not accessible in thermodynamic equilibrium is receiving much attention1–6. The theoretical concept of dynamical multiferroicity has been introduced to describe the emergence of magnetization due to time-dependent electric polarization in non-ferromagnetic materials7,8. In simple terms, the coherent rotating motion of the ions in a crystal induces a magnetic moment along the axis of rotation. Here we provide experimental evidence of room-temperature magnetization in the archetypal paraelectric perovskite SrTiO3 due to this mechanism. We resonantly drive the infrared-active soft phonon mode with an intense circularly polarized terahertz electric field and detect the time-resolved magneto-optical Kerr effect. A simple model, which includes two coupled nonlinear oscillators whose forces and couplings are derived with ab initio calculations using self-consistent phonon theory at a finite temperature9, reproduces qualitatively our experimental observations. A quantitatively correct magnitude was obtained for the effect by also considering the phonon analogue of the reciprocal of the Einstein–de Haas effect, which is also called the Barnett effect, in which the total angular momentum from the phonon order is transferred to the electronic one. Our findings show a new path for the control of magnetism, for example, for ultrafast magnetic switches, by coherently controlling the lattice vibrations with light.

show abstract