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Description:
The increasing worldwide energy consumption necessitates energy-efficient electronics and efficient means of energy storage. Contemporary batteries based on Lithium-ion or hydrogen-fuel technology are large, heavy, and due to the nature of their energy storage, explosive. Novel energy storage devices should aim to increase achievable energy densities to reduce weight and volume restrictions, but the increased energy densities should not yield increased explosion risks. Nuclear spin-based spin batteries promise just that – safely storing energy at the smallest length scales: the nuclear spin. By building up polarization in nuclear spin, energy can be safely stored in the form of so-called information entropy – eliminating any explosive dangers.
The central principle of the proposed device relies on the electron-nuclear spin-flip dynamics naturally present in topological insulator (TI) devices. TIs have the special property that the charge-conducting electrons reside on the bounding surface of the material and their intrinsic spin is coupled to their direction of motion. This well-defined spin axis allows for electron-nuclear spin exchange interactions that – by conservation of angular momentum (spin) – simultaneously flip electron and nuclear spin. Such spin exchanges between the electrons and nuclei are responsible for the build-up of nuclear polarization. In the charging phase of the battery, an applied spin-locked electronic current polarizes the nuclear ensemble. In the discharging phase of the battery, the decay of the nuclear ensemble from the polarized state back to a thermal, un-polarized, state can only be accompanied by the generation of a usable current.
Spin battery devices rely on the electron-nuclear interaction taking place in topological insulator devices. Technological advances in these devices require a thorough understanding of both the nature of TIs and the electron-nuclear interactions. Moreover, the combination of both these fields -- topological insulators and dynamical nuclear spin polarization -- is still uncharted territory.
By studying both TI materials and electron-nuclear spin interactions separately we hope to gain insights to further the development of spin battery devices and answer the central question of this work: can we model dynamical nuclear spin polarization effects in TIs to derive scaling laws for energy storage in spin battery devices?
Output:
Two publications currently on the arXiv:
- L. A. B. O. Olthof, S. R. de Wit, S.-I. Suzuki, I. Adagideli, J. W. A. Robinson, and A. Brinkman, “Multiple Andreev reflections in two-dimensional Josephson junctions\ with broken time-reversal symmetry,” Jan. 2023. arXiv:2301.02270 [cond-mat]. https://arxiv.org/abs/2301.02270
- L. Zaporski, S. R. de Wit, T. Isogawa, M. H. Appel, C. L. Gall, M. Atat ̈ure, and D. A. Gangloff, “A many-body singlet prepared by a central spin qubit,” Jan. 2023. arXiv:2301.10258 [cond-mat, physics:quant-ph] https://arxiv.org/abs/2301.10258
Pictures:
‘Dirac cone’ is an adaptation from
Elias, D., Gorbachev, R., Mayorov, A. et al. Dirac cones reshaped by interaction effects in suspended graphene. Nature Phys 7, 701–704 (2011). https://doi.org/10.1038/nphys2049