Evolution of Magnetic Double Helix and Quantum Criticality near a Dome of Superconductivity in CrAs

作者：M. Matsuda, F. Lin, R. Yu, J. Cheng, W. Wu, J. Sun, J. Zhang, P. J. Sun, K. Matsubayashi, T. Miyake, T. Kato, J.-Q. Yan, M. Stone, Q. Si, J. Luo, Y. Uwatoko · 发表于：Physical Review X · 年份：2018 · DOI：10.1103/PHYSREVX.8.031017 · 被引用次数：24 · 研究领域：Physics

At ambient pressure CrAs undergoes a first-order transition into a double-helical magnetic state at TN = 265 K, which is accompanied by a structural transition. The recent discovery of pressure-induced superconductivity in CrAs makes it important to clarify the nature of quantum phase transitions out of its coupled structural/helimagnetic order. Here we show, via neutron diffraction on the single-crystal CrAs under hydrostatic pressure (P), that the combined order is suppressed at Pc ~ 10 kbar, near which bulk superconductivity develops with a maximal transition temperature Tc ~ 2 K. We further show that the coupled order is also completely suppressed by phosphorus doping in CrAs1-xPx at a critical xc ~ 0.05, above which inelastic neutron scattering evidenced persistent antiferromagnetic correlations, providing a possible link between magnetism and superconductivity. In line with the presence of antiferromagnetic fluctuations near Pc (xc), the A coefficient of the quadratic temperature dependence of resistivity exhibits a dramatic enhancement as P (x) approaches Pc (xc), around which Res(T) has a non-Fermi-liquid form. Accordingly, the electronic specific-heat coefficient of CrAs1-xPx peaks out around xc. These properties provide clear evidences for quantum criticality, which we interpret as originating from a nearly second-order helimagnetic quantum phase transition that is concomitant with a first-order structural transition. Our findings in CrAs highlight the distinct char...