| Abrikosov vortices are quantized flux lines which penetrate through superconductors and are surrounded by superconducting currents.They emerge when type-? superconductors are in the mixed state.Superconducting vortices are sensitive to the environments around them,which enables us to realize vortex pinning and controlling by introducing intrinsic or artificial defects.For decades,vortex dynamics has been a hot topic in the superconducting research.In fundamental researches,the study of vortex motion leads to a better understanding on the nature of superconducting vortex,the properties of the materials and the mechanism of superconducting phenomena.In practical applications,the manipulation of vortex can dramatically enhance the current carrying capacity in high magnetic fields and even leads to the invention of new electronic devices.Based on the advanced nano-fabrication technology,we studied vortex dynamics using various methods such as artificial nano-defect pinning and magnetic pinning.The experiments were conducted in a 3D-magnetic-field and low-temperature measurement system.The main results are shown as follows:1.A giant superconducting rectification effect was realized by artificial nano-defect pinning.Asymmetric pinning landscapes were introduced into the superconducting micro-bridge from patterned arrays of nano-holes.As a result,the giant rectification effect was achieved in the device and the rectification signal is nearly three orders larger than previously reported one in the same material.The device can also be tuned by external magnetic fields,temperatures,etc.,resulting in a highly tunable functionality.Meanwhile,by quasi-DC transport experiments,it was confirmed that the origin of this giant rectification effect comes from a diode-like superconducting transition related to the directional supercurrents.This provides a new perspective to develop new superconducting electronic devices with a new mechanism.2.A new type of artificial-spin-ice and superconductor hybrid device was designed,in which we realized a reconfigurable superconducting switch and a programmable vortex Hall Effect.The flux quanta in the superconducting film strongly interact with the reconfigurable array of magnetic charges provided by nano-magnets underneath.In this device,vortex motion can be tuned in-situ by applying in-plane magnetic fields while other conditions remain still.We do not only realize a switchable superconducting state,but also achieve a reprogrammable vortex Hall Effect.3.Magnetic pinning was explored in high-Tc superconductors.By using a hetero-structure combining a cuprate superconductor and an artificial spin ice structure together,the vortex motion in complex environments was studied.We conducted the transport measurements and observed remarkable matching effect,which indicates the possibility of designing new hetero-structure device using high-Tc superconductors.4.A detailed research of the electron motion was conducted in unconventional electronic material systems,which provides the basic knowledges and experiences for the study of coupled superconducting vortices and electric charges in future.By measuring the magneto-resistance of topological semimetal Ce Bi,we found that anisotropic magneto-resistance was determined by the magnetization in the material.This reveals strong correlations between transport electrons and magnetism.Meanwhile,we also found an anomalous non-linear longitudinal magneto-resistance appearing in the two-dimensional-electron-gas.The origin of this phenomenon was attributed to the electron localization and impurity scattering.We confirmed that there is an unambiguous correlation between transport electrons and the amplitude of bias currents.This work provides us with the fundamental knowledge and experience for designing new hetero-structure devices and for studying the interaction between superconducting vortices and electric charges. |
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