Light induced suppression of Kondo effect at amorphous LaAlO3/SrTiO3 interface

Abstract

We report photoelectric properties of two-dimensional electron gas (2DEG) at an amorphous LaAlO3/SrTiO3 interface. Under visible light illumination (650 nm), an enhancement of electric conductivity is observed over the temperature range from 2 to 300 K. Particularly, a resistance upturn appearing below 25 K, which is further proved to from the Kondo effect, is suppressed by the 650 nm visible light. From the results of light-assisted Hall measurements, light irradiation increases the carrier mobility rather than carrier density in the Kondo regime. It is suggested that light induces the decoherence effect of localized spin states, hence the electron scattering is weakened and the carrier mobility is improved accordingly. Moreover, the enhancement of electrical conductivity by visible light verifies that in-gap states located in the SrTiO3 side of the interface play an important role in the electrical transport of the amorphous SrTiO3-based oxide 2DEG system. Our results provide deeper insight into the photoinduced effects in the 2DEG system, paving the way for the design of optoelectronic devices based on oxides.

Physics of SrTiO3-based heterostructures and nanostructures: a review

“…The Kondo upturn can be suppressed by light [402,403], even with sub-bandgap excitation of 650 nm [403]. The suppression of the Kondo effect has been attributed to light-induced charge redistribution [402] and destruction of Kondo coherence [403,404].…”

Rewritable Optical Memory Based on Sign Switching of Magnetoresistance

“…[30] A p-n junction is found to form at the interface of p-type a-C and n-type Q2DEG. Although an electron gas based on the STO surface has been extensively studied since the finding of Hwang et al in 2004, [31][32][33][34] a p-n junction between an electron gas on an STO surface and a p-type semiconductor is successfully achieved for the first time in this work. It is noted that the contact area of p-and n-type materials is nanoscale for the migration of electrons and holes.…”

Stimulating Oxide Heterostructures: A Review on Controlling SrTiO3‐Based Heterointerfaces with External Stimuli

“…It was proposed that the coherence between the localized spin centers was minimized by the light irradiation thus suppressing the Kondo effect. Concomitant with this suppression of the Kondo effect by light illumination, the mobility at the interface was enhanced from ≈50 cm 2 V −1 s −1 without light irradiation to 125 cm 2 V −1 s −1 while the carrier density was unchanged at a temperature of 2 K …”

“…Later, in LaAl 1− x Ni x O 3 /STO, it was found that the Kondo effect could be enhanced by increasing the Ni level from x = 0 to 0.05 as the dopants provided localized spin centers, but after light irradiation this effect was also reduced . Similarly, the Kondo effect was also found to be suppressed under the visible light of 650 nm in amorphous‐LAO/STO . It was proposed that the coherence between the localized spin centers was minimized by the light irradiation thus suppressing the Kondo effect.…”