Extraordinarily strong magneto-responsiveness in phase-separated LaFe2Si
Materials responding vigorously to minor variations of external stimuli with negligible hysteresis could revolutionize many of the energy technologies, including refrigeration, actuation, and sensing. We report a combined experimental and theoretical study of a two-phase composite, naturally formed at the LaFe2Si stoichiometry, which exhibits a nearly anhysteretic, two-step first-order ferromagnetic-to-paramagnetic phase transformation with enhanced sensitivity to an external magnetic field. Other unusual properties include a large plateau-like positive magnetoresistance, magnetic-field-induced temperature and entropy changes occurring over a wide temperature range, and a Griffiths-like phase associated with short-range ferromagnetic clustering in the paramagnetic state. The heat capacity, magnetization, Mössbauer spectroscopy, and electrical resistivity, all exhibit characteristic, unusually sharp, first-order discontinuities even in magnetic fields as high as 100 kOe. We expect that similar phenomena could be designed in other mixed-phase systems, leading to novel functionalities, such as giant caloric effects in many yet undiscovered or/and underperforming intermetallic compounds.
This article is published as Pathak, Arjun K., Yaroslav Mudryk, Nikolai A. Zarkevich, Dominic H. Ryan, Duane D. Johnson, and Vitalij K. Pecharsky. "Extraordinarily strong magneto-responsiveness in phase-separated LaFe2Si." Acta Materialia (2021): 117083. DOI: 10.1016/j.actamat.2021.117083.