Evidence of superconductivity (SC) has recently been reported in pressurized La3Ni2O7 and La4Ni3O10, providing a new platform to explore high-temperature superconductivity. However, while zero resistance state has been observed, experimental characterization of the superconducting properties of pressurized nickelates is still limited and experimentally challenging. Here, we present the first full temperature dependence of the upper critical field Hc2 measurement in La4Ni3O10 single crystal, achieved by combining high magnetic field and high-pressure techniques. Remarkably, the Hc2 of La4Ni3O10 is nearly isotropic, with the anisotropic parameter monotonically increasing from 1.4 near Tc to 1 at lower temperatures. By analyzing the Hc2 using the two-band model, we uncover that the anisotropic diffusivity of the bands, primarily originating from d(z2 ) and d(x2-y2 ) orbitals, is well compensated, resulting in an unusually isotropic superconducting state. These findings provide critical experimental evidence that underscores the significant role of the d(z2 ) orbital in enabling superconductivity in pressurized Ruddlesden-Popper nickelates.
@article{arxiv.2502.14410,
title = {Isotropic superconductivity in pressurized trilayer nickelate La4Ni3O10},
author = {Di Peng and Yaolong Bian and Zhenfang Xing and Lixing Chen and Jiaqiang Cai and Tao Luo and Fujun Lan and Yuxin Liu and Yinghao Zhu and Enkang Zhang and Zhaosheng Wang and Yuping Sun and Yuzhu Wang and Xingya Wang and Chenyue Wang and Yuqi Yang and Yanping Yang and Hongliang Dong and Hongbo Lou and Zhidan Zeng and Zhi Zeng and Mingliang Tian and Jun Zhao and Qiaoshi Zeng and Jinglei Zhang and Ho-kwang Mao},
journal= {arXiv preprint arXiv:2502.14410},
year = {2025}
}