arXiv subjects

Lifen Xiang

Publications and source records attributed to Lifen Xiang.

3 recordsLinked to original sources

arXiv2026

Granular Superconductivity in La$_{2}$PrNi$_{2}$O$_{7-\delta}$ Thin Films

Superconductivity realized in bilayer nickelate thin films enables direct spectroscopic and transport studies at ambient pressure. However, a persistent two-step resistive transition remains a major barrier to achieving optimal superconducting properties. Here, we show that the two-step transition in La$_2$PrNi$_2$O$_{7-\delta}$ thin films originates from the granular nature of superconductivity, specifically, the coexistence of two distinct superconducting grain phases coupled by a Josephson junction network. A secondary, lower-temperature transition appears in the $R(T)$ curve, even when residual resistance becomes vanishingly small near 30 K. This two-step behavior significantly lowers the zero-resistance transition temperature, $T_{c, zero}$$\approx$ 10 K, and limits advanced spectroscopic studies. Our findings reveal the microscopic mechanism underlying the two-step transition in thin films and underscore the need for improved oxygen homogeneity to achieve bulk superconductivity in this system.

cond-mat.supr-con↗

arXiv2025

Stabilizing and Tuning Superconductivity in La$_3$Ni$_2$O$_{7-\delta}$ Films: Oxygen Recycling Protocol Reveals Hole-Doping Analogue

The recent achievement of superconductivity in La$_3$Ni$_2$O$_{7-\delta}$ with transition temperatures exceeding 40 K in thin films under compressive strain and 80 K in bulk crystals under high pressure opens new avenues for research on high-temperature superconductivity. The realization of superconductivity in thin films requires delicate control of growth conditions, which presents significant challenges in the synthesis process. Furthermore, the stability of superconducting La$_3$Ni$_2$O$_{7-\delta}$ films is compromised by oxygen loss, which complicates their characterization. We introduce an effective recycling protocol that involves oxygen removal in a precursor phase followed by ozone-assisted annealing, which restores superconducting properties. By tuning the oxygen content, we construct an electronic phase diagram that highlights oxygen addition as a potential analogue to hole doping via La substitution with Sr, providing insights into the doping mechanism and guiding future material optimization.

cond-mat.supr-con↗

arXiv2022

Electronically phase separated nano-network in antiferromagnetic insulating LaMnO3/PrMnO3/CaMnO3 tricolor superlattice

Strongly correlated materials often exhibit an electronic phase separation (EPS) phenomena whose domain pattern is random in nature. The ability to control the spatial arrangement of the electronic phases at microscopic scales is highly desirable for tailoring their macroscopic properties and/or designing novel electronic devices. Here we report the formation of EPS nanoscale network in a mono-atomically stacked LaMnO3/CaMnO3/PrMnO3 superlattice grown on SrTiO3 (STO) (001) substrate, which is known to have an antiferromagnetic (AFM) insulating ground state. The EPS nano-network is a consequence of an internal strain relaxation triggered by the structural domain formation of the underlying STO substrate at low temperatures. The same nanoscale network pattern can be reproduced upon temperature cycling allowing us to employ different local imaging techniques to directly compare the magnetic and transport state of a single EPS domain. Our results confirm the one-to-one correspondence between ferromagnetic (AFM) to metallic (insulating) state in manganite. It also represents a significant step in a paradigm shift from passively characterizing EPS in strongly correlated systems to actively engaging in its manipulation.

cond-mat.str-el↗