Magnetic Quantum Phase Transition in {{MnSi}} under Hydrostatic Pressure
Dokumenttyp:
Zeitschriftenaufsatz
Autor(en):
Pfleiderer, C.; McMullan, G. J.; Julian, S. R.; Lonzarich, G. G.
Abstract:
The crossover from a spin-polarized to nonpolarized state as a function of pressure (p) at low temperature (T) has been investigated in MnSi via high-precision measurements of the electrical resistivity $̊ho$ and magnetic susceptibility $ḩi$. In the magnetic phase (p$<$pc$\simeq$14.6 kbar), $̊ho\propto$T2 at low T as expected for a Fermi liquid in a weakly polarized state. In the nonmagnetic phase (p$>$pc), $̊ho$ vs T is consistent with the predictions for a marginal Fermi liquid model in which nearly critical spin fluctuations of long wavelength lead to a singular quasiparticle interaction. The transition is second order for p$<$p*$\simeq$12 kbar and weakly first order in the range p*pc, where the transition temperature Tc lies below a peak of $ḩi$ vs T. The variation of Tc with p and of both $̊ho$ and $ḩi$ with T and p may be understood in terms of a model of quantum critical phenomena.