Quasilinear quantum magnetoresistance in pressure-induced nonsymmorphic superconductor chromium arsenide

Q Niu,H Kotegawa,W C Yu,Y Yanase,H Tou,E Matsuoka,H Sugawara,Swee K Goh,Z L Lim,K Y Yip

doi:10.1038/ncomms15358

Abstract

In conventional metals, modification of electron trajectories under magnetic field gives rise to a magnetoresistance that varies quadratically at low field, followed by a saturation at high field for closed orbits on the Fermi surface. Deviations from the conventional behaviour, for example, the observation of a linear magnetoresistance, or a non-saturating magnetoresistance, have been attributed to exotic electron scattering mechanisms. Recently, linear magnetoresistance has been observed in many Dirac materials, in which the electron–electron correlation is relatively weak. The strongly correlated helimagnet CrAs undergoes a quantum phase transition to a nonmagnetic superconductor under pressure. Here we observe, near the magnetic instability, a large and non-saturating quasilinear magnetoresistance from the upper critical field to 14 T at low temperatures. We show that the quasilinear magnetoresistance may arise from an intricate interplay between a nontrivial band crossing protected by nonsymmorphic crystal symmetry and strong magnetic fluctuations.

Highlights

In conventional metals, modification of electron trajectories under magnetic field gives rise to a magnetoresistance that varies quadratically at low field, followed by a saturation at high field for closed orbits on the Fermi surface
The temperature– pressure (T–p) phase diagram constructed is reminiscent of those constructed for many quantum critical systems, for example, refs 18–22, except that the magnetic transition at ambient pressure is strongly first order, the first-order signature is significantly weakened at elevated pressures[14,15]
We will show that the nonsymmorphic symmetry of the crystal structure plays an essential role on the realization of a particular band structure, leading to a nontrivial band crossing on the Brillouin zone face protected by nonsymmorphic symmetry

Summary

Introduction

Modification of electron trajectories under magnetic field gives rise to a magnetoresistance that varies quadratically at low field, followed by a saturation at high field for closed orbits on the Fermi surface. Near the magnetic instability, a large and non-saturating quasilinear magnetoresistance from the upper critical field to 14 T at low temperatures. A notable case of a striking linear MR is found in BaFe2(As1 À xPx)[2] near the antiferromagnetic quantum critical point[8], where non-Fermi liquid behaviour in the temperature (T) dependence of the resistivity (r) has been observed[9], leading to a phenomenological model to describe the electrical transport with a scattering rate that is proportional to the quadrature sum of magnetic field and temperature[8]. CrAs undergoes a strong first-order transition at TN 1⁄4 265 K into an antiferromagnetic state, in which the spins assume a double helical structure (winding axis || c axis)[12,13]. Distinct quasilinear MRs are observed in the vicinity of the magnetic instability, which we suggest is the result of an intricate interplay between having this particular band structure and the proximity to magnetic instability

Methods

Results

Conclusion