Control of nonreciprocal charge transport in topological insulator/superconductor heterostructures by Fermi level tuning and superconducting layer thickness
Soma Nagahama, Yuki Sato, Minoru Kawamura, Ilya Belopolski, Ryutaro Yoshimi, Atsushi Tsukazaki, Naoya Kanazawa, Kei S. Takahashi, Masashi Kawasaki, Yoshinori Tokura
DOI 10.1103/9l8y-zs5s · Physical Review B
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Abstract
Nonreciprocal charge transport (NCT) is defined as a phenomenon where electrical resistance depends on the current direction. It has been drawing much attention because it sensitively reflects the symmetry breaking of material systems. A topological insulator (TI)/superconductor (SC) heterostructure where the topological surface state (TSS) of the TI layer is proximitized with the SC layer is one such system that presents a sizable NCT due to a large spin-orbit coupling and superconductivity. Here, we report a control of the magnitude and sign of NCT: reversal of the direction of NCT by tuning the Fermi energy of TSS of the TI layer with respect to the charge neutral point by systematic regulation of Sb composition x in a TI/SC heterostructure of (Bi1−xSbx)2Te3/FeSe0.1Te0.9. The result is consistent with the model of a TSS proximitized with superconductivity. Furthermore, we find a significant enhancement of the magnitude of NCT in the TI/SC heterostructures by reducing the thickness of the SC layer. The enhancement can be ascribed to the inversion-symmetry breaking of the FeSe0.1Te0.9 SC-layer itself adjacent to the TI layer. Our results highlight the essential role of the TSS for exhibiting NCT and offer knobs to control the direction and magnitude of NCT.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| FeSe0.1Te0.9 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 12 | Pressure not reported | unknown |
| FeSe0.1Te0.9 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 5.5 | Pressure not reported | unknown |
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