Critical Structural Parameter Determining Magnetic Phases in the Fe2Mo3O8 Altermagnet System
A systematic structural study of the Fe2Mo3O8 system as a function of pressure, temperature, and magnetic field reveals that the P63mc space group of this material remains stable for a broad range of these parameters. No changes are seen in the long-range structure for pressures between 0 and 10 GPa, temperatures between 11 K and 300 K, and magnetic fields up to 9 T. The magnetostructural response (delta c/c) for a magnetic field transverse to the c-axis displacement is determined. The system is found to exhibit strong magnetostructural coupling. The well-known magnetic-field-induced first-order transition is found to be isostructural, between two distinct altermagnet states, and is accessible by fields in the a-b plane. In terms of the c/a ratio, the structures between ambient pressure and 10 GPa are found to map onto the full Zn doping range ((Fe1-yZny)2Mo3O8,0<y<1) in this system. The results show that the critical sensitive structural parameter for tuning the magnetic properties with pressure, temperature, and pressure is the c-axis length. The results indicate that the magnetic order in this complex metal oxide system (A2Mo3O8, A=Co, Mn, and Ni) can be cleanly tuned by pressure, making this class of materials an excellent platform for magnetic order switching in films grown on piezoelectric substrates.