Normal and inverse magnetocaloric effects in ferromagnetic Pr0.58Sr0.42MnO3

Abstract

We report magnetization, magnetic entropy change (ΔSm), and its correlation with magnetoresistance (MR) in Pr0.58Sr0.42MnO3. It is shown that the magnetization upon field-cooling shows a steplike decrease at TS = 134 K much below the ferromagnetic transition (TC = 300 K). While the low temperature transition is first-order, the high temperature transition is second-order as suggested by the hysteresis behavior in magnetization. In a magnetic field range accessible with an electromagnet, the magnetic entropy decreases at TC (ΔSm = −2.33 J/kg K with a refrigeration capacity of 65.88 J/kg for a magnetic field change of ΔH = 2 T) whereas it increases at TS (ΔSm = +0.7 J/kg K) upon magnetization. The unusual inverse magnetocaloric effect found at TS within ferromagnetic state is ascribed to orthorhombic to monoclinic structural transition. We show that ΔSm versus T curves under different magnetic fields can be collapsed into a single master curve using a scaling method. Importantly, we find that negative MR increases linearly with −ΔSm in the paramagnetic state at all magnetic fields above TC and at higher magnetic fields below TC. Such a close correlation between the magnetoresistance and the magnetic entropy change can be exploited to design efficient magnetocaloric materials.

Significant Inverse Magnetocaloric Effect induced by Quantum Criticality

“…Lastly, normal and inverse MCE for high-T c magnets have been intensively discussed for room-or near roomtemperature refrigeration [47][48][49][50][51], which helps enhance the cooling capacity and design a compact continuous refrigeration machinery [52]. Similarly, the efficient iMCE refrigerant, e.g.…”

Coexistence of normal and inverse magnetocaloric effect in inhomogeneous Ni95Cr5 layers

“…Selection of magnetic materials that exhibit both normal and inverse magnetocaloric effects (MCE) is at the core of magnetic refrigeration technology [1][2][3]. In normal MCE, the alignment of spins upon the application of a magnetic field results in a reduction of magnetic entropy ( S M D ), causing the material to heat up with the field and cool down without it [1].…”

“…New IMCE materials are important for both cooling through magnetic field application under adiabatic conditions and for use as heat sinks in conventional MCE materials [1]. IMCE materials exhibit a positive maximum in the S M D versus T curve near the antiferromagnetic (AFM) -paramagnetic (PM)/ferromagnetic (FM) transition temperature (Neel temperature, T N ) [2][3][4] and diamagnetic (DM) -paramagnetic transition temperature [5]. The IMCE behavior has been observed in some materials below the Curie temperature, T C , which is attributed to the complex magnetic structure in the ordered state [6].…”

Determination of normal and inverse magnetocaloric effect in iron oxide thin films

“…The ΔSM is a function of both H and T, but ΔSL and ΔSE are functions of T only hence ΔSM have dominant contributions when changing the strength of H. Normally, strong MCE occurs upon exposure of a magnetic material to external magnetic fields near its magnetic phase transitions (Curie temperature, TC) of the ferrimagnetic (FIM) material. However, IMCE effects have been observed near the antiferromagnetic (AFM) transition temperature (Neel temperature, TN) [5][6][7][8][9], as well as the spin glass (SG) transition temperature (TG) [1][2].…”

“…In some materials, the coexistence of both MCE and IMCE behaviors has been observed, with IMCE being observed at far lower temperatures compared to the MCE [5][6][7][8][9]. Recent findings indicate that IMCE can manifest without the requirement of AFM/SG interactions.…”