Unconventional Strong Spin-Fluctuation Effects around the Critical Pressure of the Itinerant Ising-Type Ferromagnet URhAl

Abstract

Resistivity measurements were performed for the itinerant Ising-type ferromagnet URhAl at temperatures down to 40 mK under high pressure up to 7.5 GPa, using single crystals. We found that the critical pressure of the Curie temperature exists at around $P_c$ ~ 5.2 GPa. Near $P_c$, the $A$-coefficient of the $A{T}^2$ Fermi-liquid resistivity term below $T^{\ast }$ is largely enhanced with a maximum around 5.2-5.5 GPa. Above $P_c$, the exponent of the resistivity $\rho (T)$ deviates from 2. At $P_c$, it is close to $n=5/3$, which is expected by the theory of three-dimensional ferromagnetic spin fluctuations for a 2nd-order quantum-critical point (QCP). However, $T_C(P)$ disappears as a 1st-order phase transition, and the critical behavior of resistivity in URhAl cannot be explained by the theory of a 2nd-order QCP. The 1st-order nature of the phase transition is weak, and the critical behavior is still dominated by the spin fluctuation at low temperature. With increasing pressure, the non-Fermi-liquid behavior is observed in higher fields. Magnetic field studies point out a ferromagnetic wing structure with a tri-critical point (TCP) at ~ 4.8-4.9 GPa in URhAl. One open possibility is that the switch from the ferromagnetic to the paramagnetic states does not occur simply but an intermediate state arises below the TCP as suggested theoretically recently. Quite generally, if a drastic Fermi-surface change occurs through $P_c$, the nature of the interaction itself may change and lead to the observed unconventional behavior.

9 pages, 9 figures

References in corpus (8)

• Fermi-liquid instabilities at magnetic quantum phase transitions
• Superconductivity on the border of weak itinerant ferromagnetism in UCoGe
• Signatures of valence fluctuations in CeCu2Si2 under high pressure
• Tricritical point and wing structure in the itinerant ferromagnet UGe2
• Nonanalytic paramagnetic response of itinerant fermions away and near a ferromagnetic quantum phase transition
• Quantum Metamagnetic Transitions Induced by Changes in Fermi-Surface Topology -Applications to a Weak Itinerant-Electron Ferromagnet;ZrZn_2
• Pressure Induced Quantum Phase Transitions
• Anisotropic Uniaxial Pressure Response in UCoAl Studied by Nuclear Magnetic Resonance Measurement

Cited by in corpus (11)

• Quantum Criticality in the Ferromagnetic Superconductor UCoGe under Pressure and Magnetic Field
• Wing structure in the phase diagram of the Ising Ferromagnet URhGe close to its tricritical point investigated by angle-resolved magnetization measurements
• A unified theory of ferromagnetic quantum phase transitions in heavy fermion metals
• Pressure-induced quantum phase transition in the itinerant ferromagnet UCoGa
• Effect of Pressure on Magnetism of UIrGe
• Continuous ferromagnetic quantum phase transition on an anisotropic Kondo lattice
• Pressure induced multicriticality and electronic instability in quasi-kagome ferromagnet URhSn
• Ferromagnetic quantum critical point in a locally noncentrosymmetric and nonsymmorphic Kondo metal
• Localization of 5f-electrons and pressure effects on magnetism in U intermetallics in the light of spin-fluctuation theory
• Spatially modulated, orbital selective ferromagnetism in La${}_5$Co${}_2$Ge${}_3$
• Avoided ferromagnetic quantum critical point in CeZn