Pressure-induced structural and magnetic phase transitions in ordered and disordered equiatomic FeCo

"The magnetic and structural phase diagram of equiatomic FeCo has been studied up to 45 GPa using K-edge. x-ray magnetic circular dichroism, x-ray absorption near edge spectroscopy, x-ray diffraction, and supporting. density-functional-theory-based calculations. FeCo foils with different degrees of chemical order were obtained. by magnetron sputtering. Our results show that Fe0.5Co0.5 undergo the bcc ferromagnetic to hcp nonferromagnetic. transition in the 30–45 GPa pressure range. Interestingly, the chemical order, i.e., the relative arrangements of. Fe and Co atoms, plays a major role in affecting the high-pressure structural and magnetic phase diagram of. these alloys. This result is confirmed by first-principles modeling of different structures of equiatomic FeCo. alloy. Moreover, the total-energy analysis reveals a strong competition between different magnetic hcp states. upon compression. A possible emergence of antiferromagnetism is emphasized and requires further experimental. investigation."