Magneto-Stark and Zeeman effect as origin of second harmonic generation of excitons in Cu${}_2$O

Abstract

We report on the experimental and theoretical investigation of magnetic-field-induced second harmonic generation (SHG) and two-photon absorption (TPA) of excited exciton states ($n\ge 3$) of the yellow series in Cu${}_2$O. In this centrosymmetric material, SHG can occur due to constructive interplay of electric dipole and electric quadrupole/magnetic dipole transitions for light propagating along the low-symmetry directions [111] or [112]. By application of a magnetic field in Voigt configuration, SHG gets also allowed for excitation along the [110]-axis and even the high-symmetry cubic direction [001]. Combining a symmetry analysis and a microscopic theory, we uncover the two key contributions to the magnetic-field-induced SHG: the Zeeman effect and the magneto-Stark effect. We demonstrate systematic dependencies of the SHG intensity on the linear polarization angles of the ingoing fundamental laser and the outgoing SHG beam. In general, the resulting contour plots in combination with a symmetry analysis allow one to determine uniquely the character of involved transitions. Moreover, we can separate in magnetic field the Zeeman and the magneto-Stark effect through appropriate choice of the experimental geometry and polarization configuration. We present a microscopic theory of the second harmonic generation of excitons in a centrosymmetric cubic semiconductor taking into account the symmetry and the band structure of cuprous oxide. Based on the developed microscopic theory we identify the main contributions to the second-order nonlinear susceptibility of $S$-, $P$- and $D$-excitons. We analyze the redistribution of SHG intensities between the excitonic states both in the absence and presence of the magnetic field and show good agreement with the experimental data. With increasing exciton principal quantum number the magneto-Stark effect overpowers the influence of the Zeeman effect.

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Cited by in corpus (9)

• Guide to optical spectroscopy of layered semiconductors
• Microwave-optical coupling via Rydberg excitons in cuprous oxide
• High resolution nanosecond spectroscopy of even-parity Rydberg excitons in Cu${}_2$O
• Second Harmonic Generation of cuprous oxide in magnetic fields
• Exchange interaction in the yellow exciton series of cuprous oxide
• Optical harmonic generation on the exciton-polariton in ZnSe
• Anomalous magneto-optical response and chiral interface of dipolar excitons at twisted valleys
• Tunable effective masses of magneto-excitons in two-dimensional materials
• Optical second and third harmonic generation on excitons in ZnSe/BeTe quantum wells