Structural and physical properties of Ni 1−x V _x alloys around and away from quantum critical point

Abstract

We investigate the room temperature structure (global and local), temperature dependent magnetic and transport behaviour of Ni1–xVx (0 ≤ x ≤ 0.13) alloys. Our Energy Dispersive Analysis of X-rays results show that the prepared compositions are stoichiometric. With increase in V doping, the compounds exhibit a quantum phase transition around xc = 0.12, where the ferromagnetic phase is suppressed. Our results show that all the compounds stabilize in face centred cubic structure at RT and the lattice parameter shows unusual behaviour close to xc. The magnetic and heat capacity studies show signature of Griffiths phase on either side of xc. From 25 K to the lowest collected temperature, we observe a linear T dependence of resistivity at x = 0.1 and around xc, which is separated by a Fermi-liquid region around x = 0.106. This suggests that the origin of the transport behaviour is different around the quantum critical point and away from it. Our Ni K-edge X-ray Absorption Spectroscopy results show that there is a significant reduction in the first coordination number around Ni central atom on doping. Further, with doping, there is distortion in the first coordination shell around Ni. This suggests, with V doping, the local structure around Ni is different from the global structure as obtained from the X-ray Diffraction results. Interestingly, with doping, we observe a direct connection between the extent of distortion at RT and the magnetic disorder obtained at 2 K. We believe our results will motivate the scientific community to further study the interplay between the structural disorder and quantum fluctuations with temperature at the local level.