Metastability and inverse magnetocaloric effect in doped manganite (Nd_0.25Sm_0.25Sr_0.5MnO₃) and ferromagnetic shape memory alloy (Ni₂Mn_1.36Sn_0.64): a comparison

Abstract

The manganite Nd(0.25)Sm(0.25)Sr(0.5)MnO(3) (NSSMO) shows a first-order metal to insulator transition on cooling, which is concomitant with a magnetic transition from the ferromagnetic to antiferromagnetic state. In some respect the sample shows a striking similarity with Ni-Mn-Sn based ferromagnetic shape memory alloys (FSMAs) undergoing a first-order magneto-structural transition, and efforts have been made to highlight the similarities and dissimilarities of the studied manganite with one such FSMA of composition Ni(2)Mn(1.36)Sn(0.64). From our transport and magnetic investigations, the region of transition in the NSSMO is found to be highly metastable, with a clear indication of a magnetically arrested state which persists even when the sample is cooled down to the lowest temperature of measurement. Interestingly, the studied manganite shows an inverse magnetocaloric effect similar to the FSMA. However, a striking difference between the two compositions is evident in the low-temperature magneto-transport behavior: while a clear signature of tunneling magnetoresistance is present in NSSMO due to the coexisting metallic and insulating clusters of nanometer dimension, the studied FSMA do not show such behavior due to the absence of any insulating phase in the intermetallic alloy.

Evolution of two-step magnetic transition on nanogranular Gd5Si1.3Ge2.7 thin film

“…As explained in previous report, the large volume reduction/increase across the structural transition on cooling/heating leads to a gradual arrest of the low-volume phase that hinders the structural transition and eventually suppresses (after one thousand cycles) [41]. Such effect was also verified in other Gd 5 Si x Ge 4−x compounds [24,62] and also in other compounds families presenting a first-order transition, namely the NiMnGa [63] and manganites [64]. In all the cited examples it was always the low-volume phase that became arrested.…”

Anomalous Magnetotransport Properties of Bi Doped La0.67Sr0.33MnO3

“…The resistance versus magnetic field data of Bi0 shows the polycrystalline ferromagnetic metallic manganite behaviour. Upon correlating R versus T at different applied fields and R(H)/R(0) versus H at different temperatures of Bi3 , we found the polycrystalline ferromagnetic metallic behaviour below about 10 K, the kinetic arrest of FM spins at about 30–50 K and irreversible resistance above ∼100 K. The sharp decrease in resistance of ‘virgin curve’ and subsequent hysteresis in the field cycling was seen up to the first order phase transition in case of Nd 0.25 Sm 0.25 Sr 0.5 MnO 3 and Sm 0.55 Sr 0.45 MnO 3 . The peculiar behavior in B3 sample indicates the dominant phase competition of ferromagnetic metallic and antiferromagnetic charge ordered insulating phases.…”