The effects of hydrostatic pressure on the martensitic transition, magnetic, and magnetocaloric effects of Ni 45 Mn 43 C
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Research Letter
The effects of hydrostatic pressure on the martensitic transition, magnetic, and magnetocaloric effects of Ni45Mn43CoSn11 Sudip Pandey, Department of Physics, Southern Illinois University, Carbondale, IL 62901, USA Ahmad Us Saleheen, Department of Physics & Astronomy, Louisiana State University, Baton Rouge, LA 70803, USA Abdiel Quetz, Department of Physics, Southern Illinois University, Carbondale, IL 62901, USA Jing-Han Chen, Department of Physics & Astronomy, Louisiana State University, Baton Rouge, LA 70803, USA Anil Aryal and Igor Dubenko, Department of Physics, Southern Illinois University, Carbondale, IL 62901, USA Philip W. Adams and Shane Stadler, Department of Physics & Astronomy, Louisiana State University, Baton Rouge, LA 70803, USA Naushad Ali, Department of Physics, Southern Illinois University, Carbondale, IL 62901, USA Address all correspondence to Sudip Pandey at [email protected] (Received 12 July 2017; accepted 26 September 2017)
Abstract The magnetic and magnetocaloric properties of Ni45Mn43CoSn11 have been investigated using heat capacity measurements and magnetization with hydrostatic pressure applications. A shift in the martensitic transition temperature by 40 K to higher temperatures was observed with application of pressure P = 1.06 GPa. The magnetic entropy changes significantly increases from 24 to 42 J/kgK at pressure of 0.73 GPa. A large adiabatic temperature change of 4 K was found from specific heat measurements. Also, the density of states and Debye temperature has been estimated from heat capacity measurements. The mixed effects of pressure and magnetic field on the transition temperature are discussed.
Introduction Magnetic cooling devices based on magnetocaloric effects (MCE) are considered as potential next generation energy efficient and environmentally friendly technology.[1] Due to the sharp change in magnetization (ΔM) at their respective phase transitions, some magnetic materials (e.g., intermetallic compounds including rear earth and transition metals) that undergo first order transitions (FOT) exhibit large MCEs and magnetization-dependent properties such as giant magnetoresistance, giant Hall effects, and exchange bias.[2–6] The Ni– Mn–Sn Heusler alloys provide an excellent opportunity to vary transition temperatures and magnetic state of the austenitic phase (AP) and martensitic phase (MP) by changing chemical composition or doping with different elements, which strongly influence the magnetic, magnetocaloric, and magnetoelastic properties. The parameters of magnetostructural transition (MST), such as ΔM, transition temperature, etc., in these compounds are highly sensitive to any changes in pressure, applied magnetic field, sequence of measurements and cycling, annealing temperature, heating and cooling rates, chemical composition, and the type of crystal structures. Because of the delicate balance between ionic, vibrational, magnetic, and electronic energies at an MST, large MCEs and other properties can be produced for these compounds by tuning the parameters
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