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

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 pc and around 2pc. In order to determine the extension of their NFL regions, we analyze the evolution of the resistivity p (T) ~ A(p)Tn at higher pressures. We find that in MnSi the n=3/2 exponent holds below 4.8 GPa ≈ 3pc, but it increases above that pressure. At 7.2 GPa we observe the low-temperature Fermi liquid exponent n = 2whereas for T>1.5K, n=5/3 . Our measurements in Fe show that the NFL behavior ρ ~ T5/3 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 Tonsetc (30.5 GPa)=23 K, while the A —coefficient diminishes monotonically by around 50%.