Duhan Rishabh, Sengupta Subhamita, Jesudasan John, Basistha Somak, Raychaudhuri Pratap
Tata Institute of Fundamental Research, Homi Bhabha Rd, Mumbai, 400005, India.
Nat Commun. 2025 Mar 1;16(1):2100. doi: 10.1038/s41467-025-57431-3.
"Inverse melting" refers to a rare phenomenon where an increase in temperature can induce a transition from a liquid to a solid. The vortex lattice in Type II superconductors is one system where inverse melting has been theoretically predicted. Here, we report the inverse melting of vortices in an amorphous ReZr thin film with moderate vortex pinning under the application of a magnetic field. By imaging the vortex state using a scanning tunnelling microscope, we show that at low fields and temperatures, the vortices form a "pinned liquid", that is characterised by low mobility of the vortices and vortex density that is spatially inhomogeneous. As the temperature or magnetic field is increased, the vortices get ordered, eventually forming a nearly perfect vortex solid before melting again into a liquid. Complementing direct imaging with transport measurements, we show that these transformations leave distinct signatures in the magnetotransport properties of the superconductor.
“逆熔化”指的是一种罕见现象，即温度升高会引发从液体到固体的转变。II型超导体中的涡旋晶格是一个从理论上预测会出现逆熔化的系统。在此，我们报告了在磁场作用下，具有适度涡旋钉扎的非晶态ReZr薄膜中涡旋的逆熔化现象。通过使用扫描隧道显微镜对涡旋态进行成像，我们发现，在低场和低温下，涡旋形成一种“钉扎液体”，其特征是涡旋迁移率低且涡旋密度在空间上不均匀。随着温度或磁场升高，涡旋变得有序，最终形成近乎完美的涡旋固体，然后再次熔化为液体。通过输运测量对直接成像进行补充，我们表明这些转变在超导体的磁输运特性中留下了明显的特征。
