Thrust 2 Firstprinciples Computation and Design of Layered

Thrust 2. First-principles Computation and Design of Layered Materials A. Bansil Physics Department Northeastern University Boston, Massachusetts CCDM EFRC Annual Meeting, Temple Univ. , May 4, 2015

Outline u Introduction and Overview u Goals of Thrust 2 u Synergies u Recent CCDM Supported Work u Ongoing and Planned Activities u Outlook and Conclusions

Thrust 2: Members u Adrienn Ruzsinszky [Temple; 2. 0 FTE Student] Liping Yu & Niladri Sengupta u Jianwei Sun [Temple; 1. 0 FTE Postdoc] Haowe Peng, Postdoc u Xifan Wu [Temple; 1. 0 FTE Postdoc] Zhaoru Sun, Postdoc u Arun Bansil [Northeastern, Lead] 0. 8 FTE Postdoc; 1. 0 FTE student; Bernardo Barbiellini, Senior Scientist; Ray Wang, Postdoc; Chris Lane, Baokai Wang & Hasnain Hafiz u Budgeted Faculty Time: 0. 5 -1. 0

Thrust 2: Goals First-principles computation/design of layered materials. u Test efficacy of new functionals from Thrust 1; Effects of periodic/localized defects. u Provide input for next scale modeling of Thrust 3; New materials for water-splitting, energy harvesting/ storage and other applications. u Ab initio MD for improved modeling of hydrogen production using hybrid functionals. u Spectroscopic modeling for robust

Thrust 2: Synergies u Highly integrated with other thrusts via its goals. Thrust 1 (functionls) Thrust 3 (Multi-scale) Thrust 2 Thrust 4 (experiment) Thrust 5 (experiment)

Thrust 2: Accomplishments u Has been quite productive (~ 8 months activity). 1. Han, Dai, Sun, Srolovitz, Accurate Structure, Generalized Stacking-Fault Energy, and Band-Gap Landscapes in Bilayer Materials (PRB, submitted) 2. Lu, Wu, Xiang, General microscopic model of magnetoelastic coupling from first principles, Phys. Rev. B 91, 100405(R), 2015. 3. Lee, Lu, Gu, Choi, Li, Paudel, Song, Mikheev, Kajdos, Ryu, Lee, Wu, Tenne, Oh, Stemmer, Tsymbal, Chen, Gruverman, Eom, Giant Enhancement of Ferroelectricity in a Reduced Dimension (Science, under review) 4. Wang, Wen, Miller, Zhou, Rabe, Wu, Highly polar interface phase in Ba. Ti. O 3/Ca. Ti. O 3 superlattices: enhancement of

Thrust 2: Accomplishments (contd. ) 5. Chang, Lin, Jeng, Bansil: “Thickness dependence of spin polarization and electronic structure of ultra-thin films of Mo. S 2 and related transition-metal dichalcogenides, ” Nature Scientific Reports 4, 6270 (2014). 6. Huang, Hsu, Chuang, Liu, Lin, Su, Ozolins, Bansil: “Strain driven topological phase transitions in atomically thin films of IV-V honeycomb structures, ” New Journal of Physics 16, 105018 (2014). 7. Chou, Huang, Hsu, Chuang, Liu, Lin, Bansil: “Hydrogenated ultra-thin tin films as 2 D topological insulators, ” New J. Physics 16, 115008 (2014). 8. Huang, Chou, Hsu, Chuang, Lin, Bansil: “Tunable topological electronic structure of silicene on a semiconducting Bi/Si(111)-√ 3×√ 3 substrate, ” Physical Review B 90, 245433 (2014).

Thrust 2: Accomplishments (contd. ) u 14 Invited talks at various national/international conferences [delivered or scheduled]. u Organizing/co-organizing 4 symposia at various conferences focused on layered materials. u Concrete new collaborations cutting across thrusts germinated [Sun/Srolovitz; Borguet/Bansil; between Thrusts 1 and 2]

Thrust 2: Highlights-1 u [Ruzsinszky] Developing/benchmarking a new approach for handling van der Waals interactions using SCAN meta-GGA.

Thrust 2: Highlights-2 u [Sun/Ruzsinszky/Perdew] Testing/benchmarking SCAN meta-GGA newly developed functionals. 1500 new 2 D motifs were identified, ICSD database Defect s in Si Si Phases

Thrust 2: Highlights-3 u [Wu] Stabilizing highly polar phase at perovskite superlattice interface by oxygen octahedral rotation reconstruction, BTO/CTO

Thrust 2: Highlights-4 u [Borguet/Bansil] Interaction of H with Au under optical excitation, combining experiment and theory.

Evolution of Spin Polarization: Mo. S 2, TMD’s Mono/bi layer u 1 layer: SOC driven spin split, highly polarized states at K. u 2 layers: no spin splitting (IS); external field control. u Mo. S Zhang, Chang, Zhou, 2: Direct at. Cui, Yan, Liu, Schmitt, Lee, Moore, Chen, Lin, Jeng, monolayer Hussain, Bansil, Shen, Nature Nanotech. (2014); Chang, Lin, Jeng & Bansil, Sci. Reports (2014)

Sn films as 2 D-QSH TIs: Stanenes/Stananes Iodine decoration u Large band gap QSH phases predicted in stanenes/stananes (1 -3 BL) u I-terminated films non-trivial insulator for 1 BL, semimetal BL Liu, Lin and Bansil, New J. Phys. (2014) Chou, Huang, for Hsu, 2 -4 Chuang,

Silicene: Spin-Orbit Coupling & External 0<E <E E =E SOC/E = 0 Fields No SOC E >E z K Gap vs Ez QSH phase z c Critical z c Band insulator B A Ec Tsai, Huang, Chang, Lin, Jeng, Bansil, Nature Commun. (2013) Ez

Spintronics Applications Spin Filte r Spin separat or Logic Devic e Tsai, Huang, Chang, Lin, Jeng, Bansil, Nature Commun. (2013); Gupta et al. , App. Phys. Lett. 104, 032410 (2014); Sarri et al. , App. Phys. Lett. 104 (2014)

Ongoing, Near Future Activities u [Sun] High throughput screening, defect engineering to identify interesting layered materials. u [Wu] Continued testing of advanced functionals; Develop experimentally validated design rules for interfaces/surfaces. u [Ruzsinszky] Further develop advanced functionals for treating van der Walls bonding; application to semiconducting/metallic bilayers; Other properties. u [Bansil] Spin-polarization and topological

Summary & Conclusions u Thrust 2 has hit the ground running, and has started to make significant contributions toward an improved understanding and modeling of layered materials. u This pace will further accelerate as the synergistic activities within and across thrusts continue to grow.