Neutron, electron and X-ray scattering investigation of Cr1-xVx near Quantum Criticality

TL;DR

This study investigates how doping Cr with V affects its electronic and magnetic properties near quantum criticality, revealing a new charge order that prevents the formation of a quantum critical point.

Contribution

It provides experimental evidence of a doping-induced charge instability in Cr-V alloys that stabilizes a new order, avoiding quantum criticality.

Findings

Suppression of spin density wave with V doping

Discovery of a new charge order at x_c=0.037

Restructuring of Fermi surface near critical doping

Abstract

The weakness of electron-electron correlations in the itinerant antiferromagnet Cr doped with V has long been considered the reason that neither new collective electronic states or even non Fermi liquid behaviour are observed when antiferromagnetism in Cr$_{1-x}$V$_{x}$ is suppressed to zero temperature. We present the results of neutron and electron diffraction measurements of several lightly doped single crystals of Cr$_{1-x}$V$_{x}$ in which the archtypal spin density wave instability is progressively suppressed as the V content increases, freeing the nesting-prone Fermi surface for a new striped charge instability that occurs at x$_{c}$=0.037. This novel nesting driven instability relieves the entropy accumulation associated with the suppression of the spin density wave and avoids the formation of a quantum critical point by stabilising a new type of charge order at temperatures in excess of 400 K. Restructuring of the Fermi surface near quantum critical points is a feature found in materials as diverse as heavy fermions, high temperature copper oxide superconductors and now even elemental metals such as Cr.