Soft point-contact Andreev reflection spectroscopy in a palm-type cubic anvil-pressure cell

Qingxin Dong; Fengrui Shi; Yan Zhang; Tong Shi; Yi Liu; Shaoheng Ruan; Zhongjin Wu; Jianping Sun; Zhaoming Tian; Yoshiya Uwatoko; Guanghan Cao; Xin Lu; Bosen Wang; Jin-Guang Cheng

arXiv · 2607.10668

Soft point-contact Andreev reflection spectroscopy in a palm-type cubic anvil-pressure cell

Qingxin Dong·Fengrui Shi·Yan Zhang·Tong Shi·Yi Liu·Shaoheng Ruan·Zhongjin Wu·Jianping Sun·Zhaoming Tian·Yoshiya Uwatoko·Guanghan Cao·Xin Lu·Bosen Wang·Jin-Guang Cheng

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Abstract

We have implemented soft point-contact Andreev reflection spectroscopy (PCARS) in a palm-type cubic anvil pressure cell by combining a substrate anchoring strategy with an external wire-splitting technique. This design enables the stable formation of multiple point contact junctions under hydrostatic pressures up to 15 GPa. Benchmark measurements on the elemental superconductor Nb demonstrate high reproducibility and yield a zero-temperature superconducting gap with a gap ratio of 3.3. We further apply this technique to the Kagome metal superconductor CsCr3Sb5 and the bilayer nickelate superconductor La2PrNi2O7. Pronounced zero-bias conductance peaks are observed, and their evolution with temperature, magnetic field and applied pressure is investigated, together with the superconducting gap magnitude and possible pairing symmetries. These measurements provide spectroscopic evidence consistent with unconventional superconductivity in these materials. Our work establishes a robust experimental platform that bridges macroscopic electrical transport and microscopic spectroscopic probes, opening a new avenue for investigating pairing symmetry in a wide range of pressure-induced unconventional superconductors.

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Qingxin Dong, Fengrui Shi, Yan Zhang, Tong Shi, Yi Liu, Shaoheng Ruan, Zhongjin Wu, Jianping Sun, Zhaoming Tian, Yoshiya Uwatoko, Guanghan Cao, Xin Lu, Bosen Wang, Jin-Guang Cheng. 2026-07-12. Soft point-contact Andreev reflection spectroscopy in a palm-type cubic anvil-pressure cell. https://arxiv.org/abs/2607.10668

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