Cylinder vortex of superconductor in TaSe₃topological ring crystals

Abstract

Abstract. Topology has many applications in modern condensed matter physics. We report that superconducting properties are changed by topology. We have measured the magnetic torque of the ring-shaped crystals of TaSe3 by using piezoresistive cantilevers in order to investigate the superconducting topological properties. We measured two ring samples. The outer radius of sample A was 37.9 µm and that of sample B was 24.5 µm. We found that the magnetic torque of the ring crystals changes periodically by increasing of the external magnetic field. The periodicity of sample A was 1.85 Gauss and that of sample B was 4.75 Gauss, respectively. We found that the period is proportional to the circumference of the ring crystal rather than the area enclosed by the outer circumference. In that case, it is natural that vortices in the ring crystal were placed along the circumference. From these results, we suggest that vortices exist as cylinder vortices in the rings at the results of topological effects of superconductive ring-shaped crystals, and this matter give a new experimental evidence of topological effect in superconductor. IntroductionWhat kind of effects on the superconducting state, such as a mixed state of type II superconductors, are caused by topology?At the mixed state vortices penetrate the superconductor when the applied magnetic field increases beyond H c1 . Typically, Abrikosov lattice is the most stable configuration of voltices with repulsive force interaction to each other. However, when the system size is small, shape of superconductors, such as boundary condition, affects penetration and arrangement of vortices [1]. Similarly, topology of systems has a potential of affecting the superconducting properties. For example, closed systems like ring crystals [2], vortices may not relocate to become stable like bulk superconductors, because they are trapped globally in the hole of the crystals. Furthermore, systems like Möbius ring crystals [3], there is the possibility that vortices cannot penetrate crystals. These speculations suggest that topology of systems plays an important role in physical properties.The purpose of this research is to investigate the effects of topology on superconducting properties. The ring-shaped crystals of quasi-one-dimensional superconductor TaSe 3 are suitable to investigate these topological effects, because it is expected that TaSe 3 causes topological effects for its filamentary structure. Besides that, a measurement without electrode is appropriate to investigate those effects, because this method conserves topology of systems. Therefore, we adopted magnetic torque measurement without electrode by using micro cantilevers [4]. As a result, we found a phenomenon that the magnetic torque of the ring crystals oscillates

Electrically Insulating Flexible Films with Quasi‐1D van der Waals Fillers as Efficient Electromagnetic Shields in the GHz and Sub‐THz Frequency Bands

“…Surprisingly, selenium-deficient TaSe3 can be produced from even selenium-rich CVT conditions. [34,50,51] Stoichiometric TaSe3 has been isolated from high pressure conditions and selenium-flux growth. [33,52] Although selenium deficiency does not seem to affect the overall electrical conductivity of TaSe3 or its Tc, [15,37,43,[45][46][47] several studies indicate that doping can modify its electronic structure.…”

Metallic vs. semiconducting properties of quasi-one-dimensional tantalum selenide van der Waals nanoribbons

“…32,33 Rather unexpectedly, selenium deficiency in TaSe 3 has been reported even in selenium-rich CVT atmospheres. 30,34,35 Some studies of bulk crystals indicate that the background doping also can adjust the electronic structure of TaSe 3 . 20,24,28,29,36 For example, as the sulfur content increases in the mixed TMT Ta (S x Se 1−x ) 3 , it becomes semiconducting, 37 while TaSe 3 with indium impurity exhibits a metal-to-insulator transition.…”