Fig. 3
From: Restoration of quantum critical behavior by disorder in pressure-tuned (Mn,Fe)Si
Static local field, ordered volume fraction and dynamic relaxation rate in (Mn,Fe)Si and MnSi. a–d: MuSR results for (Mn0.85Fe0.15)Si in ZF (a–c) and in LF = 500 G (d). a Temperature and pressure dependence of the magnetically ordered volume fraction determined by ZF-MuSR. b Static muon spin relaxation rate σ, which is proportional to the ordered moment size. c Pressure dependence of the magnetic volume fraction and the static spin relaxation rate at T ~ 250 mK (lowest temperature achievable by the 3He cryostat), demonstrating the continuous evolution of the order parameter σ from zero in the paramagnetic phase to finite values in the ordered phase, and the development of static magnetic order in the full volume fraction in the ordered phase at low temperatures. d Dynamic relaxation rate 1/T 1 observed in LF = 500 G. The sharp peak of 1/T 1 is a signature of dynamic critical behavior expected for a second-order thermal phase transition. e, f Results of a previous MuSR study13 in pure MnSi, replotted here to be contrasted to those of (Mn,Fe)Si. Panel e demonstrates that the ordered moment size, proportional to the ZF MuSR frequency, changes discontinuously at the phase boundary, while the magnetic volume fraction changes continuously. Panel f demonstrates that the dynamic critical behavior is suppressed with increasing pressure and completely eliminated at p = 12.7 kbar for MnSi. This behavior in MnSi is characteristic of first-order quantum evolution
