Suppression of the bulk high spin–low spin transition by doping the chiral magnet MnGe

Abstract

In the MnGe chiral magnet, the helimagnetic order and local moment collapse in two steps, showing the succession of high spin (HS) and low spin (LS) states as pressure increases. Here, we use high-pressure neutron diffraction to study the doped compounds Mn 0.86 Co 0.14 Ge and Mn 0.9 Rh 0.1 Ge, and show that the evolution of their microscopic magnetic properties is instead continuous. It means that the bulk HS-LS transition is a unique feature of pure MnGe, very sensitive to small changes of the band structure and easily suppressed by chemical substitution. On the other hand, the helimagnetic correlations appear to be strengthened by doping and survive up to larger pressures (≈19 GPa, to be compared with ≈13 GPa). We discuss these results in the light of other disordered systems with remarkable properties, the so-called Invar alloys.

Ambient Pressure Synthesis of Re-Substituted MnGe and Its Magnetic Properties

“…These discoveries are important for spintronics and lead to an active search for materials with nontrivial behaviors [8,10]. Such properties of the B20-type members as helimagnetism, multigap superconductivity, field-induced skyrmion lattices, high-spin to low-spin transition, quantum phase transitions, and chiral topological fermions are widely discussed [6,7,[11][12][13][14]. Particular attention is drawn to magnetic skyrmions, which were first discovered in MnSi and Fe 1−x Co x Si [12,15].…”