Quantum phase transition and Fermi liquid behavior inPd1−xNixnanoalloys

Abstract

The Pdt_xNE alloy system is an established ideal transition-metal system possessing a composition-induced paramagnetic-to-ferromagnetic quantum phase transition (QPT) at the critical concentration xc ~ 0.026 in bulk. A low-temperature non-Fermi liquid (NFL) behavior around xc usually indicates the presence of quantum criticality (QC) in this system. In this work, we explore the existence of such a QPT in nanoparticles of this alloy system. We synthesized single-phase, polydispersed and 40-50 nm mean diameter crystalline nanoparticles of Pdi^N i* alloys, with x near xc and beyond, by a chemical reflux method. In addition to the determination of the size, composition, phase, and crystallinity of the alloys by microscopic and spectroscopic techniques, the existence of a possible QPT was explored by resistivity and dc magnetization measurements. A dip in the value of the exponent n near xc, and a concomitant peak in the constant A of the AT" dependence of the low-temperature (T) resistivity indicate the presence of a quantum-like phase transition in the system. The minimum value of n, however, remains within the Fermi liquid regime (n > 2). The dc magnetization results suggest an anticipatory presence of a superparamagnetic-to-ferromagnetic QPT in the mean-sized nanoparticles. The observation of a possible quantum critical NFL behavior (n < 2) through resistivity is argued to be inhibited by the electron-magnon scatterings present in the smaller nanoparticles.

Exploring quantum Griffiths phase in Ni1−x V x nanoalloys

“…4(b). Both the Ni and V peaks can be seen to vary monotonically and essentially concurrently with x , confirming the Ni-V alloy formation with different V concentrations, as also reported earlier 13, 29 . Further, to ensure that the samples are really metallic as required, electrical resistivity ρ has been measured as a function of temperature on tightly pressed pellets of some representative NP’s.…”

“…It is anticipated that possible existence of a QCP could be integrated with the quantum physical phenomena exhibited by nanoparticles 11, 12 and exploited technologically. This inquisitiveness led the authors earlier to investigate the occurrence of QPT in Ni x Pd 1− x nanoalloy system 13 , which was found to exhibit a QPT in spite of not showing any NFL behaviour. If one rather wants to explore QGP’s, wherein structure and magnetism are correlated as described above, the intricacies of magnetic NP structure and related magnetism vis-a-vis QGP scenario have to be examined first.…”

“…Ni nanoparticles 19–22 and Ni-V alloy microparticles 23 have earlier been synthesized and shown to possess FM 19, 20 , SPM 21 , photocatalytic 22 and hydrogen-storage 23 properties. In a recent study 13 , we prepared rather Ni x Pd 1− x NP’s by a chemical reflux method. A chemical reflux method can also be tried for preparing Ni 1− x V x NP’s.…”

Quantum phase transition and ferromagnetism inCo1+xSn

“…In some solid-solution alloys of type M 1-x T x [2,17,18] magnetic transition-metal elements (T) cause the nonmagnetic metal (M) to become a ferromagnet above some critical concentration x c .…”

3$d$ - 4$d$ hybridization anomaly in Ni$_x$Pd$_{1-x}$ alloys at quantum critical point

“…Perhaps the most easily understandable class of a QPT is the ferromagnet-to-paramagnet (FM-PM) transition at 0 K in itinerant electron systems as a function of the strength of exchange interaction between electron spins [8]. The FM-PM QPT occurring in metallic Ni x Pd 1−x alloy system across its QCP (x c = 0.026) is one such example, wherein signatures of quantum criticality have been observed in bulk macroscopically [4] and microscopically [9], and in nanodimensions macroscopically [10].…”