Critical behavior, universal magnetocaloric, and magnetoresistance scaling of MnSi

We report the critical behavior of a B20 cubic compound MnSi, known by its helical, conical and skyrmion phases in low fields, in its magnetic field-induced ferromagnetic (high-field) phase by means of magnetic-entropy (magnetoresistance) methods. The evaluated critical exponents are $\ensuremath{\beta}=0.25\ifmmode\pm\else\textpm\fi{}0.02(0.19\ifmmode\pm\else\textpm\fi{}0.04),\ensuremath{\gamma}=1.29\ifmmode\pm\else\textpm\fi{}0.27(1.32\ifmmode\pm\else\textpm\fi{}0.16)$, and $\ensuremath{\delta}=6.18\ifmmode\pm\else\textpm\fi{}0.28(7.79\ifmmode\pm\else\textpm\fi{}0.52)$. The self-consistency of the newly adopted methods is established by comparing the thus obtained exponents with those estimated using the modified Arrott's plot method and neutron diffraction. The field controlling parameter is $n\ensuremath{\sim}0.5$ and its deviation from the mean-field model exponent confirm the weak first-order and field-induced ferromagnetic behavior. A direct proportional relation between magnetic entropy and magnetoresistance infers itinerant magnetic nature. The collapse of high-field data onto the more generalized magnetic-entropy master curve confirms the field-induced first- to second-order phase transition and thereby tricritical phenomenon in MnSi.