Superconductivity in chromium nitrides Pr3Cr10-xN11 with strong electron correlations

Wei Wu; Kai Liu; Yanjie Li; Zhenhai Yu; Desheng Wu; Yuting Shao; Shihang Na; Gang Li; Ruizhen Huang; Tao Xiang; Jianlin Luo

doi:10.1093/nsr/nwz129

Superconductivity in chromium nitrides Pr₃Cr_10-xN₁₁ with strong electron correlations

Natl Sci Rev. 2020 Jan;7(1):21-26. doi: 10.1093/nsr/nwz129. Epub 2019 Sep 2.

Authors

Wei Wu^{1

2}, Kai Liu³, Yanjie Li^{1

2}, Zhenhai Yu⁴, Desheng Wu^{1

2}, Yuting Shao^{1

2}, Shihang Na^{1

2}, Gang Li^{1

5}, Ruizhen Huang^{2

6}, Tao Xiang^{1

2

6}, Jianlin Luo^{1

2

5}

Affiliations

¹ Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
² School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China.
³ Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing 100872, China.
⁴ School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China.
⁵ Songshan Lake Materials Laboratory, Dongguan 523808, China.
⁶ Kavli Institute for Theoretical Sciences, Beijing 100190, China.

Abstract

Exploration of superconductivity in Cr-based compounds has attracted considerable interest because only a few Cr-based superconductors (CrAs, A₂Cr₃As₃ and ACr₃As₃ (A = K, Rb, Cs, Na)) have been discovered so far and they show an unconventional pairing mechanism. We report the discovery of bulk superconductivity at 5.25 K in chromium nitride in Pr₃Cr_10-xN₁₁ with a cubic lattice structure. A relatively large upper critical field of H _c2(0) ∼ 12.6 T is determined, which is larger than the estimated Pauli-paramagnetic pair-breaking magnetic field. The material has a large electronic specific-heat coefficient of 170 mJ K^-2 mol^-1-about 10 times larger than that estimated by the electronic structure calculation, which suggests that correlations between 3d electrons are very strong in Pr₃Cr_10-xN₁₁, and thus quantum fluctuations might be involved. Electronic structure calculations show that the density of states at the Fermi energy are contributed predominantly by Cr 3d electrons, implying that the superconductivity results mainly from the condensation of Cr 3d electrons. Pr₃Cr_10-xN₁₁ represents a rare example of possible unconventional superconductivity emerging in a 3D system with strong electron correlations. Nevertheless, clarification of the specific pairing symmetry needs more investigation.

Keywords: Cr-based superconductors; nitrides; strong electron correlations; unconventional superconductivity.