Pressure effects on the electronic properties of the undoped superconductor ThFeAsN

• Published in: Physical review. B 2018-04, Vol.97 (14), Article 140506
• Main Authors: Barbero, N., Holenstein, S., Shang, T., Shermadini, Z., Lochner, F., Eremin, I., Wang, C., Cao, G.-H., Khasanov, R., Ott, H.-R., Mesot, J., Shiroka, T.
• Format: Article
• Language: English
• Subjects: Deformation; Group 5A compounds; Iron; Magnetic induction; Muon spin rotation; NMR; Nuclear magnetic resonance; Organic chemistry; Penetration depth; Pressure effects; Spin-lattice relaxation; Temperature dependence
• ISSN: 2469-9950; 2469-9969
• DOI: 10.1103/PhysRevB.97.140506

The recently synthesized ThFeAsN iron pnictide superconductor exhibits a Tc of 30 K, the highest of the 1111-type series in the absence of chemical doping. To understand how pressure affects its electronic properties, we carried out microscopic investigations up to 3 GPa via magnetization, nuclear magnetic resonance, and muon-spin rotation experiments. The temperature dependence of the As75 Knight shift, the spin-lattice relaxation rates, and the magnetic penetration depth suggest a multiband s±-wave gap symmetry in the dirty limit, whereas the gap-to-Tc ratio Δ/kBTc hints at a strong-coupling scenario. Pressure modulates the geometrical parameters, thus reducing Tc as well as Tm, the temperature where magnetic-relaxation rates are maximized, both at the same rate of approximately −1.1K/GPa. This decrease in Tc with pressure is consistent with band-structure calculations, which relate it to the deformation of the Fe 3dz2 orbitals.