Direct Rashba spin-orbit interaction in Si and Ge nanowires with different growth directions

Kloeffel, Christoph and Rancic, Marko J. and Loss, Daniel. (2018) Direct Rashba spin-orbit interaction in Si and Ge nanowires with different growth directions. PHYSICAL REVIEW B, 97 (23). p. 235422.

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Official URL: https://edoc.unibas.ch/69214/

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We study theoretically the low-energy hole states in Si, Ge, and Ge/Si core/shell nanowires (NWs). The NW core in our model has a rectangular cross section, the results for a square cross section are presented in detail. In the case of Ge and Ge/Si core/shell NWs, we obtain very good agreement with previous theoretical results for cylindrically symmetric NWs. In particular, the NWs allow for an unusually strong and electrically controllable spin-orbit interaction (SOI) of Rashba type. We find that the dominant contribution to the SOI is the "direct Rashba spin-orbit interaction" (DRSOI), which is an important mechanism for systems with heavy-hole-light-hole mixing. Our results for Si NWs depend significantly on the orientation of the crystallographic axes. The numerically observed dependence on the growth direction is consistent with analytical results from a simple model, and we identify a setup where the DRSOI enables spin-orbit energies of the order of millielectronvolt in Si NWs. Furthermore, we analyze the dependence of the SOI on the electric field and the cross section of the Ge or Si core. A helical gap in the spectrum can be opened with a magnetic field. For this gap, we obtain the largest g factors for magnetic fields applied perpendicular to the NW and parallel to the electric field.
Faculties and Departments:05 Faculty of Science > Departement Physik > Physik > Theoretische Physik Mesoscopics (Loss)
UniBasel Contributors:Loss, Daniel
Item Type:Article, refereed
Article Subtype:Research Article
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:08 Oct 2019 09:14
Deposited On:08 Oct 2019 09:14

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