물리학과 특별세미나 개최 안내

1. 연사: 이대수 박사 (Seoul National University)
2. 일시: 2018. 4. 5(목), 오후 2시
3. 장소: 공학3동 201호 (세미나실)
4. 제목: On-demand heterostructure control of hidden-in-bulk states

A major challenge in condensed matter physics is predictive control of physical properties and functions in complex materials. In this talk, I will demonstrate a heterostructuring approach to engineer free-energy landscape and stabilize a new state, otherwise away from equilibrium, in a controlled way. First, as a model material, I choose an archetypal correlated material vanadium dioxide (VO2) [1], which has the insulating ground state of the monoclinic phase. A designed heterostructure suppresses the electronic correlation without changing the crystal structure in this otherwise correlated insulator. It stabilizes a nonequilibrium metallic state, leading to an isostructural metal-insulator transition. In addition, I will show emergence of an ordered ferroelectric state in ultrathin films of an otherwise non-ferroelectric SrTiO3 [2–4]. This challenges the long-standing notion that a collective order (e.g., ferroelectricity) is inevitably suppressed at the scale of a few nanometers. These discoveries highlight the ability to control the hidden-in-bulk states in heterostructures, as well as provide new insights for exploring complex materials.

[1] D. Lee et al. (under review)
[2] D. Lee et al., Science 349, 1314 (2015)
[3] H. Lu*, D. Lee* et al., Nano Lett. 18, 491 (2018)
[4] D. Lee et al. (under review)