Quantum phase transitions in spiral magnets without inversion center
a Prokhorov General Physics Institute of the Russian Academy of Sciences, ul. Vavilova 38, Moscow, 119942, Russian Federation
b National Research University Higher School of Economics, ul. Myasnitskaya 20, Moscow, 101000, Russian Federation
c Moscow Institute of Physics and Technology (State University), Institutskii per. 9, Dolgoprudnyi, Moscow Region, 141700, Russian Federation
d The National Research Center "Kurchatov Institute", Konstantinov Petersburg Nuclear Physics Institute, Orlova Roshcha, Gatchina, Leningradskaya Region, 188300, Russian Federation
It is shown that the T − x magnetic phase diagram of Mn1-xFexSi solid solutions exhibits two quantum critical points: x* ~ 0.11, which corresponds to the disappearance of long-range spiral magnetic order, and xc ~ 0.24, which marks the suppression of the phase with short-range magnetic order It is established that the macroscopic reason for observed complicated quantum critical behavior is the evolution of the Fermi-surface driven by an increase of the iron concentration.