Probing the extended non-Fermi liquid regimes of MnSi and Fe

TL;DR

This study investigates the pressure-dependent non-Fermi liquid behavior of MnSi and Fe, revealing extended NFL regimes and their evolution into Fermi liquid states at high pressures, with implications for understanding quantum criticality.

Contribution

It provides detailed resistivity measurements under high pressure, mapping the evolution of NFL behavior and identifying the pressure ranges where Fermi liquid behavior emerges in MnSi and Fe.

Findings

MnSi exhibits NFL behavior with n=3/2 below 4.8 GPa, transitioning to Fermi liquid at 7.2 GPa.

Fe shows NFL behavior with rho T^{5/3} up to 30.5 GPa, beyond the superconducting region.

Superconducting transition temperature decreases significantly under pressure, with A-coefficient reducing by 50%.

Abstract

Recent studies show that the non-Fermi liquid (NFL) behavior of MnSi and Fe spans over an unexpectedly broad pressure range, between the critical pressure p_c and around 2p_c. In order to determine the extension of their NFL regions, we analyze the evolution of the resistivity rho(T) A(p)T^n at higher pressures. We find that in MnSi the n=3/2 exponent holds below 4.8 GPa=3 p_c, but it increases above that pressure. At 7.2 GPa we observe the low temperature Fermi liquid exponent n=2 whereas for T>1.5 K, n=5/3. Our measurements in Fe show that the NFL behavior rho T^{5/3} extends at least up to 30.5 GPa, above the entire superconducting (SC) region. In the studied pressure range, the onset of the SC transition reduces by a factor 10 down to T_c^onset(30.5 GPa)=0.23 K, while the A-coefficient diminishes monotonically by around 50%.