Co-reporter:Chao Jing, Yang Liu, Dong Zheng, Xiaolong Wang, Junkun Sun, Yuanlei Zhang, Changqin Liu, Dongmei Deng, Zhenjie Feng, Kun Xu, Zhe Li
Solid State Communications 2016 Volume 241() pp:32-37
Publication Date(Web):September 2016
DOI:10.1016/j.ssc.2016.05.006
•A large zero-field cooled exchange-bias effect was observed in Ni50Mn35Fe2In13.•A non-monotonic behavior of spontaneous HEB appears in Ni50Mn35Fe2In13.•The maximal value of GMR reaches −57% under ΔH=50 kOe in Ni50Mn33Fe4In13.In the present work, we have obtained a large zero-field cooled exchange-bias (spontaneous exchange bias, SEB) in Ni50Mn35Fe2In13 Heusler alloy. The experimental results indicate that the sample with x=2 exhibits super-spin glass (SSG), super-paramagnetic (SPM), super-ferromagnetic (SFM) and antiferromagnetic (AFM) behaviors in the martensite state at low temperature. Contributing to the complex magnetic interactions, a large SEB effect with the value of 1567 Oe was obtained at 5 K. At the same time, a non-monotonic behavior of spontaneous exchange bias field (spontaneous HEB) was observed with the variation of temperature, which is resulted from the competition between the volume fraction of SFM clusters and the exchange coupling of the SFM–AFM interface. In addition, during martensitic transformation (MT), extraordinary electrical transport properties of Ni50Mn37−xFexIn13 (x=2–4) alloys have been observed under various external magnetic field. The maximal value of the giant magnetoresistance (GMR) reaches about 57% at 135 K under the external magnetic field change of 50 kOe. The effect of field induced reverse martensitic transformation (FIRMT) on the GMR has been also discussed.
Co-reporter:Zhe Li, Yuanlei Zhang, Kun Xu, Taoxiang Yang, Chao Jing, Hao Lei Zhang
Solid State Communications 2015 Volume 203() pp:81-84
Publication Date(Web):February 2015
DOI:10.1016/j.ssc.2014.11.023
•Both of the lattice and the spin components to the entropy changes is separated in this alloy.•The inverse MCE only originates from contribution of lattice entropy change in this alloy.•The lattice contribution works against the magnetic contribution to the entropy changes.In this paper, the changes of volume fractions between austenitic and martensitic phase have been carefully deduced through magnetization data for polycrystalline Ni46.7Co5Mn33In15.3 alloy during reverse martensitic transformation at different magnetic fields. On this basis, the contributions of the lattice and the spin components to the total entropy changes could be effectively separated by using the Clausius–Clapeyron equation and the Debye theory calculations. It is concluded that the lattice contribution works against the magnetic contribution to the inverse magnetocaloric effect (MCE) in this alloy. Further analysis indicates that the effective inverse MCE comes from field-induced variation of the crystal structure. On the contrary, the change of the magnetic moment alignment in this process yields negative contribution, leading to a reduction of the total inverse MCE by about 33%.
