Magnetic properties of the itinerant ferromagnet LaCrGe3 under pressure studied by 139La NMR

TL;DR

This study uses $^{139}$La NMR under pressure to investigate the magnetic properties of LaCrGe$_3$, revealing robust Cr moments and three-dimensional ferromagnetic spin fluctuations in the paramagnetic state.

Contribution

It provides the first detailed pressure-dependent NMR analysis of LaCrGe$_3$, showing the stability of Cr moments and the nature of spin fluctuations.

Findings

Cr moments are robust under pressure up to 2.64 GPa.

Ferromagnetic order develops below ~50 K at high pressures.

Spin fluctuations are three-dimensional ferromagnetic above $T_C$.

Abstract

$^{139}$La nuclear magnetic resonance (NMR) measurements under pressure ($p = 0-2.64$ GPa) have been carried out to investigate the static and dynamic magnetic properties of the itinerant ferromagnet LaCrGe$_3$. $^{139}$La-NMR spectra for all measured pressures in the ferromagnetically ordered state show a large shift due to the internal field induction $|$$B_{\rm int}$$|$ $\sim$ 4 T at the La site produced by Cr ordered moments. The change in $B_{\rm int}$ by less than 5\% with $p$ up to 2.64~GPa indicates that the Cr 3$d$ moments are robust under pressure. The temperature dependence of NMR shift and $B_{\rm int}$ suggest that the ferromagnetic order develops below $\sim$ 50~K under higher pressures in a magnetic field of $\sim$ 7.2 T. Based on the analysis of NMR data using the self-consistent-renormalization (SCR) theory, the spin fluctuations in the paramagnetic state well above $T_{\rm C}$ are revealed to be three dimensional ferromagnetic throughout the measured $p$ region.