Stable room-temperature multiferroic skyrmions in lithium niobate with enhanced Pockels effect

TL;DR

This paper reports the discovery of stable multiferroic skyrmions in lithium niobate at room temperature, significantly enhancing its Pockels effect and opening new avenues for high-efficiency optical and magnetic devices.

Contribution

First observation of multiferroic skyrmions in lithium niobate, demonstrating enhanced Pockels effect and stability for potential applications in magnetoelectric devices.

Findings

Multiferroic skyrmions exhibit high stability in lithium niobate.

The Pockels coefficient is nearly tripled to 101 pm/V.

Electro-optical modulation efficiency is significantly improved.

Abstract

Lithium Niobate (LN) is a ferroelectric material with exceptional electrical characteristics, including high piezoelectricity, high Pockels effect, etc. These properties make it a promising platform for numerous fields such as high-speed communication, optical computation, and quantum information processing. Besides these, the introduction of magnetic structures to LN holds significant potential to achieve magnetoelectric coupling, which can be applied in magnetic memory and data-processing devices with high efficiency. Here, for the first time, we observe a special topological magnetic structure called magnetic skyrmion in LN (SK-LN) by the combination of magnetic field annealing and rapid annealing processes . Compared to the magnetic skyrmions reported in magnetic systems, SK-LN exhibit exceptionally high stability. Additionally, the center of the magnetic vortex exhibits spontaneous ferroelectric polarization, indicating its multiferroic characteristic. With the excitation of these multiferroic skyrmions, the modulation efficiency of the electro-optical (EO) modulator fabricated on thin film lithium niobate on insulator (LNOI) wafer was found to be enhanced from 1.98 V*cm to 0.63 V*cm. It is considered that the multiferroic skyrmions significantly enhance the Pockels coefficient of LN to 101 pm/V, nearly three times the result (32pm/V) reported previously.