Magnetic phase transition in the itinerant helimagnet $\mathrm{MnSi}$: Thermodynamic and transport properties

Magnetic phase transition in the itinerant helimagnet $MnSi$ : Thermodynamic and transport properties

S. M. Stishov, A. E. Petrova, S. Khasanov, G. Kh. Panova, A. A. Shikov, J. C. Lashley, D. Wu, and T. A. Lograsso

Phys. Rev. B 76, 052405 – Published 16 August 2007

Abstract

A careful study of thermodynamic and transport properties of a high-quality single crystal of $MnSi$ at ambient pressure suggests that its transition to a helical magnetic state near $29 K$ is weakly first order. The heat capacity, temperature derivative of resistivity, thermal expansion, and magnetic susceptibility exhibit a specific structure around the phase transition point, interpreted as a combination of first- and second-order features. Striking mirror symmetry between the temperature derivative of resistivity and the thermal expansion coefficient is observed. Conclusions drawn from these experiments question prevailing views on the phase diagram of $MnSi$ .