Field Dependence of the Magnetic Quantum Phase Transition in {{MnSi}}

We report on precision measurements of the AC susceptibility in high-purity samples of MnSi as a function of pressure up to 16 kbar, field up to 7 T and temperature down to 30 mK. In zero field it has previously been shown, that the weakly spin polarised (ordered) phase collapses above a critical pressure Pc = 14.6 kbar. The normal metallic state at this quantum phase transition was thereby reported to be consistent with the presence of a highly dispersive spectrum of magnetic fluctuations. Our new results reveal that a field polarised state is restored above Pc by application of a magnetic field, which can be considered as a further sensitive control parameter to tune a quantum critical regime. The crossover between the non-polarised and polarised regimes is characterised by a strongly field and pressure dependent maximum in $ḩi$ characteristic of itinerant electron metamagnetism.     «

We report on precision measurements of the AC susceptibility in high-purity samples of MnSi as a function of pressure up to 16 kbar, field up to 7 T and temperature down to 30 mK. In zero field it has previously been shown, that the weakly spin polarised (ordered) phase collapses above a critical pressure Pc = 14.6 kbar. The normal metallic state at this quantum phase transition was thereby reported to be consistent with the presence of a highly dispersive spectrum of magnetic fluctuations. Our...     »