Extraordinarily strong magneto-responsiveness in phase-separated LaFe2Si

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2021-08-15
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Pathak, Arjun
Mudryk, Yaroslav
Zarkevich, Nikolai
Johnson, Duane
Ryan, Dominic
Johnson, Duane
Pecharsky, Vitalij
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Ames Laboratory
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Ames LaboratoryMaterials Science and Engineering
Abstract

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.

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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.

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