Presentation Information
[PC5-05]Non-reciprocal transport caused by in-plane vortices in 2-dimensional superconductors with asymmetric barriers
*Yuichiro Shiroki1, Yusuke Kato1,2 (1. Dept. of Phys., Univ. of Tokyo (Japan), 2. Dept. of Basic Sci., Univ. of Tokyo (Japan))
Keywords:
vortex,thin film,non-reciprocal voltage,non-equilibrium state
[Purpose]
Non-reciprocal transport is the phenomenon where voltage depends on the direction of the injected current and is also reported for thin-film FeSe in existence of magnetic field.
In the experiment, two different insulators sandwich the thin-film FeSe and break the inversion symmetry of the whole system. This is why non-reciprocal transport emerges even though FeSe has inversion symmetry in its crystal structure. And most surprisingly, the non-reciprocal voltage experiences sign switching when the applied magnetic field is increased.
Our research motivations are to reproduce the sign switching of the non-reciprocal voltage and to propose a hypothesis about the mechanism.
[Method]
Based on time-dependent Ginzburg-Landau equation, numerical calculations are conducted by using py-TDGL package. By letting GL parameter alpha modulate spatially, asymmetry of the boundaries is incorporated.
[Results]
Under different film thicknesses, degrees of asymmetry, initial states and currents, the system evolves along with time-dependent Ginzburg-Landau equation. In a low magnetic region, vortices at the edge are pinned and never move. In a rather high magnetic field, however, after sufficiently long time, vortices come out from one edge to the other side periodically. The motion of vortices gives rise to a finite voltage in the direction of the current. Taking the time average voltage of both directions of currents, non-reciprocal voltage was calculated.
We found in some series of parameters that non-reciprocal voltage changes its sign at the specific magnetic field.
[Consideration]
The slope of the GL parameter alpha near the edges of the film is considered to control the magnetic field where non-reciprocal voltage switches. Also, the thickness of the film is considered to play a key role in non-reciprocal voltage because the behavior of non-reciprocal voltage versus magnetic field looks very different. Further consideration is necessary about the mechanism of them.
[Conclusion]
Although the values of the parameters are quite different from those of the experiment, we successfully confirmed that non-reciprocal voltage changes its sign at a specific magnetic field. Further calculations will be performed in order to propose the hypothesis about the mechanism.
[References]
[1] J. E. Villegas et al., A Superconducting Reversible Rectifier That Controls the Motion of Magnetic Flux Quanta.Science302,1188 1191(2003). [2] Ando, F., Miyasaka, Y., Li, T. et al. Observation of superconducting diode effect. Nature 584, 373–376 (2020). [3] Yasuda, K., Yasuda, H., Liang, T. et al. Nonreciprocal charge transport at topological insulator/superconductor interface. Nat Commun 10, 2734 (2019). [4] M. Hashimoto(2024).Observation and Control of Interface-induced Magnetotransport Phenomena, Graduate School of Arts and Sciences, Master’s thesis (The University of Tokyo)
Non-reciprocal transport is the phenomenon where voltage depends on the direction of the injected current and is also reported for thin-film FeSe in existence of magnetic field.
In the experiment, two different insulators sandwich the thin-film FeSe and break the inversion symmetry of the whole system. This is why non-reciprocal transport emerges even though FeSe has inversion symmetry in its crystal structure. And most surprisingly, the non-reciprocal voltage experiences sign switching when the applied magnetic field is increased.
Our research motivations are to reproduce the sign switching of the non-reciprocal voltage and to propose a hypothesis about the mechanism.
[Method]
Based on time-dependent Ginzburg-Landau equation, numerical calculations are conducted by using py-TDGL package. By letting GL parameter alpha modulate spatially, asymmetry of the boundaries is incorporated.
[Results]
Under different film thicknesses, degrees of asymmetry, initial states and currents, the system evolves along with time-dependent Ginzburg-Landau equation. In a low magnetic region, vortices at the edge are pinned and never move. In a rather high magnetic field, however, after sufficiently long time, vortices come out from one edge to the other side periodically. The motion of vortices gives rise to a finite voltage in the direction of the current. Taking the time average voltage of both directions of currents, non-reciprocal voltage was calculated.
We found in some series of parameters that non-reciprocal voltage changes its sign at the specific magnetic field.
[Consideration]
The slope of the GL parameter alpha near the edges of the film is considered to control the magnetic field where non-reciprocal voltage switches. Also, the thickness of the film is considered to play a key role in non-reciprocal voltage because the behavior of non-reciprocal voltage versus magnetic field looks very different. Further consideration is necessary about the mechanism of them.
[Conclusion]
Although the values of the parameters are quite different from those of the experiment, we successfully confirmed that non-reciprocal voltage changes its sign at a specific magnetic field. Further calculations will be performed in order to propose the hypothesis about the mechanism.
[References]
[1] J. E. Villegas et al., A Superconducting Reversible Rectifier That Controls the Motion of Magnetic Flux Quanta.Science302,1188 1191(2003). [2] Ando, F., Miyasaka, Y., Li, T. et al. Observation of superconducting diode effect. Nature 584, 373–376 (2020). [3] Yasuda, K., Yasuda, H., Liang, T. et al. Nonreciprocal charge transport at topological insulator/superconductor interface. Nat Commun 10, 2734 (2019). [4] M. Hashimoto(2024).Observation and Control of Interface-induced Magnetotransport Phenomena, Graduate School of Arts and Sciences, Master’s thesis (The University of Tokyo)