Events at Physics |
Events on Monday, February 24th, 2014
- Plasma Physics (Physics/ECE/NE 922) Seminar
- Transport Properties of Strongly Coupled Plasmas
- Time: 12:00 pm - 1:00 pm
- Place: 2241 Chamberlin
- Speaker: Scott Baalrud, University of Iowa
- Host: Cary Forest
- Condensed Matter Theory Group Seminar
- Valleytronics in Silicon: the Principles and the Practice
- Time: 4:30 pm
- Place: Chamberlin 5310
- Speaker: Andre Saraiva, University of Wisconsin
- Abstract: Alternative schemes for information processing are being pursued by the industry. Spintronics - the most prominent candidate for alternative electronics - explores an internal degree of freedom of electrons, namely the spin, in order to encode information. Recent advances in the manipulation of the valley degree of freedom[1] of certain semiconductors are opening the possibility for a third option: Valleytronics. But in order to achieve useful control of valley, large enough valley-orbit induced valley splitting (VS) must be achieved.
We will present three ways to control valleys on a scale higher than 1 meV:
a) in a quantum well, the adoption of a barrier constituted of a layered heterostructure might lead to constructive reflection if the layer thicknesses match the electron wavelength, in analogy with a Bragg mirror [2];
b) the disparity between the high valley splitting in a impurity donor potential and the low splitting in a Si/Insulator interface may be harnessed controlling the tunneling between these two states, so that the valley splitting may be controlled digitally [3];
c) intrinsic Tamm/Shockley interface states might strongly hybridize with conduction states, leading to a much enhanced valley splitting[4,5], and its contribution to the 2DEG ground state may be experimentally identified [6].
1. D. Culcer, A. L. Saraiva, Belita Koiller, Xuedong Hu, and S. Das Sarma, PRL *108*, 126804 (2012).
2. L. Zhang, J.-W. Luo, A Saraiva, Belita Koiller, Alex Zunger, Nature Comm. *4*, 2396 (2013)
3. A. Baena, A. L. Saraiva, Belita Koiller, and M. J. CalderA3n, PRB 86, 035317 (2012).
4. K. Takashina, Y. Ono, A. Fujiwara, Y. Takahashi and Y. Hirayama, *PRL* *96, *236801 (2006).
5. A. Saraiva, Belita Koiller and M. Friesen, Phys. Rev. B *82*, 245314 (2010).
6. A. Dusko, A. Saraiva and Belita Koiller, arXiv:1310.6878 (2013). - Host: Perkins