Abstract Body

Coupling between complex oxides can induce new properties at the interface of heterostructures which are absent in the individual oxides, resulting in materials for novel applications ¹. Pavlov et. al reported superconductivity at 30 K in a heterostructure consisting of an insulating ferroelectric (Ba_0.8Sr_0.2TiO₃) film deposited on a non-atomically flat surface of insulating La₂CuO₄ single crystal ². Additionally, superconductivity at 30 K was reported in the literature ³ in bilayers of an insulator La₂CuO₄ and a metal La₅Sr₅CuO₄, neither of which is superconducting in isolation.

Our research aims to utilise the property of one oxide layer in a thin film heterostructure to alter the property of the second oxide layer, in this case, a ferroelectric Ba_0.8Sr_0.2TiO₃ (BSTO) deposited on a La_2-xBa_xCuO₄ (LBCO) layer. LBCO is a high-temperature superconductor which exhibits an anomalous dip in the superconducting critical temperature (Tc) at a hole concentration corresponding to x ≈ 0.125 ⁴. BSTO on the other hand is a ferroelectric material and as such, can be polarised by the application of an electric field. Our hypothesis is that the edge of the Tc dip for LBCO (Ba ≈ 0.125) can be exploited in a heterostructure to control the superconducting state of LBCO using electric fields. We anticipate that application of an electric field across the heterostructure, polarises the ferroelectric, which in turn alters the carrier concentration in the LBCO (Ba ≈ 0.125) film at the interface such that it can be switched in and out of the superconducting state. If switching can be achieved, these heterostructures have potential application as energy-efficient memory elements in superconducting and quantum computers.

In this poster, preliminary results from studies on ferroelectric Ba_0.8Sr_0.2TiO₃ and La_2-xBa_xCuO₄ (x = 0.16 and 0.13) thin films deposited from lab-grown ceramic targets using magnetron sputtering will be presented.

References

1. Pavlov, D. P., et al. "Properties of the interface of Ba0.8Sr0.2TiO3/LaMnO3 heterostructure." Ferroelectrics 575.1 (2021): 123-129.
2. Pavlov, Dmitrii P., et al. "Fabrication of high-temperature quasi-two-dimensional superconductors at the interface of a ferroelectric Ba0.8Sr0.2TiO3 film and an insulating parent compound of La2CuO4." Physical review letters 122.23 (2019): 237001.
3. Pavlov, Dmitrii P., et al. "Tailoring high temperature quasi-two-dimensional superconductivity." arXiv preprint arXiv:1804.05519 (2018).
4. Agterberg, Daniel F., et al. "The physics of pair-density waves: Cuprate superconductors and beyond." Annual Review of Condensed Matter Physics 11 (2020): 231-270.

Acknowledgment

We acknowledge funding from MacDiarmid Institute of Advanced Materials and Nanotechnology