Quantum critical point followed by Kondo-like behavior due to Cu substitution in itinerant, antiferromagnet ${\text{La}}_2{\text{(Cu}}_x{\text{Ni}}_{1-x}{)}_7$

Abstract

${\text{La}}_2{\text{Ni}}_7$ is an itinerant magnetic system with a small ordered moment of $\sim$ 0.1 ${\mu }_B/\text{Ni}$ and a series of antiferromagnetic (AFM) transitions at $T_1$ = 61.0 K, $T_2$ = 56.5 K and $T_3$ = 42.2 K. $M(H)$, and $\rho (H)$ isotherms as well as constant field $M(T)$ and $\rho (T)$ measurements on single crystalline samples manifest a complex, anisotropic $H-T$ phase diagram with multiple phase lines. Here we present the growth and characterization of single crystals of the ${\text{La}}_2{\text{(Cu}}_x{\text{Ni}}_{1-x}{)}_7$ series for 0 $\le x\le$ 0.181. We measured powder x-ray diffraction, and composition, as well as anisotropic $R(H,T)$, $M(H,T)$, and $C_p(T)$ on these single crystals. Using the measured data, we infer a $(T-x)$ phase diagram to study the evolution of the AFM ordering upon Cu substitution. For $0\le x\le 0.097$, the system remains magnetically ordered at base temperature with $x\le$ 0.012, showing signs of multiple AFM ordering temperatures. For the higher substitution levels, $0.125\le x\le 0.181$, there are no signatures of magnetic ordering, but anomalous features in $R(T)$ and $C_p(T)$ data are observed which are consistent with the Kondo effect in this system. The intermediate $x$ = 0.105 sample lies between the magnetic ordered and the Kondo regime and is in the vicinity of the AFM-quantum critical point (QCP). Thus, ${\text{La}}_2{\text{(Cu}}_x{\text{Ni}}_{1-x}{)}_7$ is an example of a small moment system that can be tuned through a QCP. Given these data combined with the fact that the ${\text{La}}_2{\text{Ni}}_7$ structure has kagome-like, Ni-sublattices running perpendicular to the crystallographic $c$ axis, and a predicted $3d$-electron flat band that contributes to the density of states near the Fermi energy, ${\text{La}}_2{\text{(Cu}}_x{\text{Ni}}_{1-x}{)}_7$ becomes a promising system to host and study exotic physics.

25 pages, 29 figures

References in corpus (25)

• Fermi-liquid instabilities at magnetic quantum phase transitions
• High-temperature superconductivity in iron-based materials
• Quantum Criticality in Heavy Fermion Metals
• Superconductivity on the border of weak itinerant ferromagnetism in UCoGe
• YSix closely related YbT${}_2$Zn${}_{20}$ (T = Fe, Co, Ru, Rh, Os, Ir) heavy fermion compounds with large local moment degeneracy
• Quantum phases driven by strong correlations
• Frustration and the Kondo effect in heavy fermion materials
• Pressure induced superconductivity on the border of magnetic order in MnP
• A flat band-induced correlated kagome metal
• Fermi Surface Reconstruction without Breakdown of Kondo Screening at Quantum Critical Point
• Signatures of the Kondo effect in VSe2
• Magnetic field tuned quantum criticality of heavy fermion system YbPtBi
• Non-Fermi liquid behavior in a correlated flatband pyrochlore lattice
• Formation of short-range magnetic order and avoided ferromagnetic quantum criticality in pressurized LaCrGe${}_3$
• Emergent flat band and topological Kondo semimetal driven by orbital-selective correlations
• Multiple temperature scales of the periodic Anderson model: the slave bosons approach
• Avoided ferromagnetic quantum critical point in pressurized La${}_5$Co${}_2$Ge${}_3$
• Exceedingly Small Moment Itinerant Ferromagnetism of Single Crystalline La${}_5$Co${}_2$Ge${}_3$
• Small moment antiferromagnetic ordering in single crystalline La2Ni7
• Weak itinerant magnetic phases of La2Ni7
• Unusual coercivity and zero field stabilization of fully saturated magnetization in single crystals of LaCrGe${}_3$
• Energy Scales of the Doped Anderson Lattice Model
• Electronic signatures of successive itinerant, magnetic transitions in hexagonal La2Ni7
• Kondo-like behavior in a mixed valent oxypnictide $\mathrm{L}{\mathrm{a}}_3\mathrm{C}{\mathrm{u}}_4{\mathrm{P}}_4{\mathrm{O}}_2$
• Effect of Ni substitution on the fragile magnetic system ${\text{La}}_5{\text{Co}}_2{\text{Ge}}_3$