Structural and magnetic phase diagram of CrAs and its relationship with pressure-induced superconductivity

Abstract

Most unconventional superconductors, including cuprates and iron-based superconductors, are derived from chemical doping or application of pressure on their collinearly magnetic-ordered parent compounds [1][2][3][4][5] . The recently discovered pressure-induced superconductor CrAs, as a rare example of a non-collinear helimagnetic superconductor, has therefore generated great interest in understanding microscopic magnetic properties and their interplay with superconductivity 6-8 . Unlike cuprates and iron based superconductors where the magnetic moment direction barely changes upon doping, here we show that CrAs exhibits a spin reorientation from the ab plane to the ac plane, along with an abrupt drop of the magnetic propagation vector at a critical pressure (P c ≈ 0.6 GPa). This magnetic phase transition coincides with the emergence of bulk superconductivity, indicating a direct connection between magnetism and superconductivity. With further increasing pressure, the magnetic order completely disappears near the optimal T c regime (P ≈ 0.94 GPa). Moreover, the Cr magnetic moments between nearest neighbors tend to be aligned antiparallel with increasing pressure toward the optimal superconductivity regime. Our findings suggest that the non-collinear helimagnetic or-

Anomalous anisotropic compression behavior of superconducting CrAs under high pressure

“…Based on the experimental results of ref. 21, this suggests that the magnetism of CrAs may exhibit changes such as an abrupt drop of the magnetic propagation vector at a critical pressure (∼0.6 GPa) (21). In addition, the large decrease of b axis observed in the present work has not been reported by Shen et al (21).…”

“…It was shown that CrAs exhibits metallic conductivity over the entire range of pressure and temperature considered. Recently, Shen et al investigated the structural and magnetic phase diagram of CrAs as a function of the temperature and pressure (21). The experimental results indicated that a spin reorientation was induced above the critical pressure (∼0.6 GPa).…”

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

“…Recently, Keller et al [27] and Shen et al [26] performed high-pressure neutron diffraction experiments on polycrystalline CrAs samples and found evidences in support of the possible connection between magnetism and SC. In particularly, Shen et al [26] reported a pressure-induced spin reorientation from the ab to the ac plane with an abrupt reduction of  at around 6 kbar, above which  is well below 0.3. However, our results in Fig.…”

“…Notably, this latter observation on the single-crystal sample is different from what observed on the polycrystalline samples that always show a sudden contraction across TN. [26] The chemical pressure applied via P substitution for As in CrAs1-xPx plays the same role as the external pressure in suppressing the structural transition of CrAs. As shown in Fig.…”

Tripletpz-wave pairing in quasi-one-dimensionalA2Cr3As3superconductorsWu1, Yang2, Le3 et al. 2015Phys. Rev. BSelf Cite100101093View full textAdd to dashboardCite

“…Their superconducting mechanism shown in many experimental results [13][14][15][16] is very likely related to electron-electron interactions. Among the families of the chromium-based superconductors, the Q1D A 2 Cr 3 As 3 (A=K,Rb,Cs) superconductors family [10][11][12] , which has T c up to 6.1 K 10 at ambient pressure, is particularly intriguing.…”