Center for Correlated Electron Systems

Seminar

Complex oxide thin films and heterointerfaces: from novel phenomena to oxide electronics

August 29, 2019l Hit 237
Date : September 2, 2019 14:00 ~ 15:30
Speaker : Dr. Kun Han(Nanyang Technological University)
Location : Bldg. 19, Rm. 210

Complex oxide thin films and heterointerfaces exhibit an incredible variety of intriguing phenomena. A remarkable example is the realization of two-dimensional electron gases (2DEGs) in LaAlO 3 /SrTiO 3 (LAO/STO) heterointerface, which has stimulated extensive efforts toward the understanding of fundamental physics and developing all-oxide electronic devices.

However, the carrier density (electron mobility) of the STO-based 2DEG is much higher (lower) than that of conventional semiconductors. In this presentation, it will be demonstrated that the electron mobility can be dramatically enhanced by replacing LAO with other perovskite oxides, such as (LaAlO 3 ) 0.3 (Sr 2 AlTaO 6 ) 0.35 and Sr(Al 0.5 Ta 0.5 )O 3 , which have better lattice-matching and symmetry-matching [1]. Furthermore, the orbital occupancy and carrier distribution of the 2DEGs at the STO-based heterointerfaces can be modulated by electric field effect (back gate and ionic liquid gate), which results in the observation of 1/B-period quantum Shubnikov deHaas oscillations [2] and B-period quantum Aharonov-Bohm oscillations. In addition, the practical device applications of complex oxide thin films and heterostructures are demonstrated.

The water-dissolvable and recyclable electronic device based on an erasable and recreatable 2DEG at the amorphous Sr 3 Al 2 O 6 /STO (a-SAO/STO) heterointerface is created [3].

Freestanding VO 2 membranes with flexibility and metal-insulator transition (MIT) are synthesized by etching of sacrificial water-soluble SAO layers.

REFERENCES

1. Z. Huang # , K. Han # , S. W. Zeng, et al., Nano Lett 16, 2307 (2016).

2. K. Han, Z. Huang, S. W. Zeng, et al., Phys. Rev. Mater. 1, 011601(R) (2017).

3. K. Han, K. Hu, X. Li, et al., Sci. Adv. 5, eaaw7286 (2019).

 

 

Host: Prof. Tae Won Noh