Hole spins have gained considerable interest in the past few years due to their potential for fast electrically controlled qubits. Here, we study holes confined in Ge hut wires, a so-far unexplored type of nanostructure. Low-temperature magnetotransport measurements reveal a large anisotropy between the in-plane and out-of-plane g-factors of up to 18. Numerical simulations verify that this large anisotropy originates from a confined wave function of heavy-hole character. A light-hole admixture of less than 1% is estimated for the states of lowest energy, leading to a surprisingly large reduction of the out-of-plane g-factors compared with those for pure heavy holes. Given this tiny light-hole contribution, the spin lifetimes are expected to be very long, even in isotopically nonpurified samples.
The work was supported by the EC FP7 ICT project SiSPIN no. 323841, the EC FP7 ICT project PAMS no. 610446, the ERC Starting Grant no. 335497, the FWF-I-1190-N20 project, and the Swiss NSF. We acknowledge F. Schäffler for fruitful discussions related to the hut wire growth and for giving us access to the molecular beam epitaxy system, M. Schatzl for her support in electron beam lithography, and V. Jadris ̌ko for helping us with the COMSOL simulations. Finally, we thank G. Bauer for his continuous support.
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Watzinger H, Kloeffel C, Vukusic L, et al. Heavy-hole states in germanium hut wires. Nano Letters. 2016;16(11):6879-6885. doi:10.1021/acs.nanolett.6b02715
Watzinger, H., Kloeffel, C., Vukusic, L., Rossell, M., Sessi, V., Kukucka, J., … Katsaros, G. (2016). Heavy-hole states in germanium hut wires. Nano Letters, 16(11), 6879–6885. https://doi.org/10.1021/acs.nanolett.6b02715
Watzinger, Hannes, Christoph Kloeffel, Lada Vukusic, Marta Rossell, Violetta Sessi, Josip Kukucka, Raimund Kirchschlager, et al. “Heavy-Hole States in Germanium Hut Wires.” Nano Letters 16, no. 11 (2016): 6879–85. https://doi.org/10.1021/acs.nanolett.6b02715.
H. Watzinger et al., “Heavy-hole states in germanium hut wires,” Nano Letters, vol. 16, no. 11, pp. 6879–6885, 2016.
Watzinger H, Kloeffel C, Vukusic L, Rossell M, Sessi V, Kukucka J, Kirchschlager R, Lausecker E, Truhlar A, Glaser M, Rastelli A, Fuhrer A, Loss D, Katsaros G. 2016. Heavy-hole states in germanium hut wires. Nano Letters. 16(11), 6879–6885.
Watzinger, Hannes, et al. “Heavy-Hole States in Germanium Hut Wires.” Nano Letters, vol. 16, no. 11, American Chemical Society, 2016, pp. 6879–85, doi:10.1021/acs.nanolett.6b02715.