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 p c and around 2 p c . In order to determine the extension of their NFL regions, we analyze the evolution of the resistivity ρ ( 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 ρ ∼ 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%.