Ferromagnetic Critical Behavior in U(Co${}_{1-x}$Fe${}_x$)Al ($0\le x\le 0.02$) Studied by ${}^{59}$Co Nuclear Quadrupole Resonance Measurement

Abstract

In order to investigate physical properties around a ferromagnetic (FM) quantum transition point and a tricritical point (TCP) in the itinerant-electron metamagnetic compound UCoAl, we have performed the ${}^{59}$Co nuclear quadrupole resonance (NQR) measurement for the Fe-substituted U(Co${}_{1-x}$Fe${}_x$)Al ($x$ = 0, 0.5, 1, and 2%) in zero external magnetic field. The Fe concentration dependence of ${}^{59}$Co-NQR spectra at low temperatures indicates that the first-order FM transition occurs at least above $x$ = 1%. The magnetic fluctuations along the $c$ axis detected by the nuclear spin-spin relaxation rate $1/T_2$ exhibit an anomaly at $T_{\max }$ $\sim$ 20 K and enhance with increasing $x$. These results are in good agreement with theoretical predictions and indicate the presence of prominent critical fluctuations at the TCP in this system.

6 pages, 7 figures

References in corpus (2)

• Tricritical point and wing structure in the itinerant ferromagnet UGe2
• Anisotropic Uniaxial Pressure Response in UCoAl Studied by Nuclear Magnetic Resonance Measurement

Cited by in corpus (3)

• Longitudinal spin fluctuations driving field-reinforced superconductivity in UTe${}_2$
• Effect of Pressure on Magnetism of UIrGe
• Emergence of Elastic Softening Featuring Ultra-Slow Dynamics Around Magnetic Critical Endpoint in UCoAl