InN超导中的磁通钉扎性质研究

The superconductivity in InN is the foundation for the all III-V semiconductor based superconductor/semiconductor integration. To study the flux pinning properties of InN superconductor, the I-V relationships, R-B transitions, and R-T transitions are investigated. The scaling results of I-V curves indicate there is a vortex glass-liquid transition. The R-T curves are well fitted by thermally activated flux flow (TAFF) model. The TAFF activated energy satisfies a power-law relationship with magnetic field, but it has two different exponents under the low magnetic field and high magnetic field. We explain it as the result of a transition from single flux pinning to collective flux pinning which also leads to the rapid attenuation of critical current as the magnetic field increases. By analyzing the temperature dependence of critical current, we found the dominant δL-pinning mechanism. Furthermore, the dependence of pinning force on magnetic field is analyzed using the Dew-Hughes model, and the results show that the main pinning center is the point pinning. Our work paves the way for studying III-nitrides based hybrid superconductor-semiconductor devices.