Theoretical prediction of a highly responsive material: Spin fluctuations and superconductivity in FeNiB₂ system

Journal Article · 29 October 2019 · Applied Physics Letters

DOI: https://doi.org/10.1063/1.5124489 · OSTI ID:1574820

Wang, Renhai ^[1]; Sun, Yang  ^[2]; Antropov, Vladimir ^[2]; Lin, Zijing ^[3]; Wang, Cai-Zhuang ^[4]; Ho, Kai-Ming ^[5]

---

1. Univ. of Science and Technology of China, Hefei (China). Dept. of Physics; Ames Lab., Ames, IA (United States)
2. Ames Lab., Ames, IA (United States)
3. Univ. of Science and Technology of China, Hefei (China). Dept. of Physics
4. Ames Lab., Ames, IA (United States); Iowa State Univ., Ames, IA (United States). Dept. of Physics
5. Ames Lab., Ames, IA (United States); Iowa State Univ., Ames, IA (United States). Dept. of Physics; University of Science and Technology of China, Hefei (China). International Center for Quantum Design of Functional Materials (ICQD), Hefei National Lab. for Physics Science at the Microscale

By analyzing the Fe-Ni-B compositional diagram, we predict an energetically and dynamically stable FeNiB₂ compound. This system belongs to the class of highly responsive state of materials, as it is very sensitive to the external perturbations. This state is also characterized by a high level of spin fluctuations, which strongly influence possible magnetic long- and short-range orders. Furthermore, we demonstrate that these antiferromagnetically dominating fluctuations could lead to the appearance of spin mediated superconductivity. The obtained results suggest a promising avenue for the search of strong spin fluctuation systems and related superconductors. Spin fluctuations (SFs) in itinerant electron magnets play an important role in many metallic systems including weak itinerant magnets, heavy fermion compounds, actinides, Invar alloys, and many magnetoresistive materials. SFs also have been identified in high-temperature superconductors and recently discovered Fe-based superconductors with a clear suggestion about their crucial influence on the mechanisms of unconventional superconductivity. In the majority of cases, superconductivity appears near the magnetic quantum critical point, where magnetism has a pure itinerant character with no local moments involved. This is exactly a case when quantum SFs (including spin zero-point motion) are strong and provide a dominating contribution to many observable physical properties. However, as a typical example, in a case of superconductivity, the direct calculations and prediction of critical temperature from first principles are still not possible. In this situation, one can focus on searching for materials with a strong level of SF, leading to the possible development of promising physical properties. In this paper, we will introduce qualitatively the concept of a highly responsive state (HRS) (see Fig. 1). This term is used here to indicate that a physical system is in a state characterized by an order parameter, which is very sensitive to the external perturbations (pressure, magnetic fields, etc.). The HRS is naturally related to closeness to the instability and, as usual in such situations, one can expect that fluctuations are very important.

• Research Organization: Ames Laboratory (AMES), Ames, IA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division
• Grant/Contract Number: AC02-07CH11358
• OSTI ID: 1574820
• Report Number(s): IS-J--10080
• Journal Information: Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 18 Vol. 115; ISSN 0003-6951
• Publisher: American Institute of Physics (AIP)Copyright Statement
• Country of Publication: United States
• Language: English