Huge Upper Critical Field and Electronic Instability in Pressure-induced Superconductor CeIrSi3 without Inversion Symmetry in the Crystal Structure

• Published in: Journal of the Physical Society of Japan 2008-07, Vol.77 (7)
• Main Authors: SETTAI, Rikio, MIYAUCHI, Yuichiro, TAKEUCHI, Tetsuya, LEVY, Florence, SHEIKIN, Ilya, ONUKI, Yoshichika
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Heavy-fermion superconductors; Physics; Pressure effects; Superconducting materials (excluding high-tc compounds); Superconductivity; Transition temperature variations
• ISSN: 0031-9015; 1347-4073
• DOI: 10.1143/jpsj.77.073705

We measured low-temperature electrical resistivity in a magnetic field as a function of pressure, and studied the superconducting property of CeIrSi3 with a non-centrosymmetric tetragonal structure. CeIrSi3 is an antiferromagnet with a Néel temperature TN=5.0 K at ambient pressure, but the antiferromagnetic ordering disappears completely at a pressure Pc=2.25 GPa. Superconductivity appears in a wide pressure region from 1.8 to about 3.5 GPa, with a maximum transition temperature Tsc\\simeq1.6 K at Pc*\\simeq2.63 GPa. At around Pc*, the upper critical field Hc2 for the magnetic field H along the [0 0 1] direction is not destroyed by spin polarization based on Zeeman coupling but possesses an upturn curvature below 1 K, revealing a divergent tendency of Hc2 at Pc*, with a huge Hc2(0)\\simeq450 kOe. On the other hand, the upper critical field for H||[110] indicates the tendency of Pauli paramagnetic suppression, with Hc2(0)=95 kOe at 2.65 GPa. This might be a combined phenomenon between the electronic instability at Pc* and the characteristic superconducting property without inversion symmetry in the tetragonal structure.