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Spin-Valve-Like Magnetoresistance in Mn2NiGa at Room Temperature

Singh, Sanjay and Rawat, R and Muthu, S Esakki and D'Souza, SW and Suard, E and Senyshyn, A and Banik, S and Rajput, P and Bhardwaj, S and Awasthi, AM and Ranjan, Rajeev and Arumugam, S and Schlagel, DL and Lograsso, TA and Chakrabarti, Aparna and Barman, SR (2012) Spin-Valve-Like Magnetoresistance in Mn2NiGa at Room Temperature. In: PHYSICAL REVIEW LETTERS, 109 (24).

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Official URL: http://dx.doi.org/10.1103/PhysRevLett.109.246601 ...


Spin valves have revolutionized the field of magnetic recording and memory devices. Spin valves are generally realized in thin film heterostructures, where two ferromagnetic (FM) layers are separated by a nonmagnetic conducting layer. Here, we demonstrate spin-valve-like magnetoresistance at room temperature in a bulk ferrimagnetic material that exhibits a magnetic shape memory effect. The origin of this unexpected behavior in Mn2NiGa has been investigated by neutron diffraction, magnetization, and ab initio theoretical calculations. The refinement of the neutron diffraction pattern shows the presence of antisite disorder where about 13% of the Ga sites are occupied by Mn atoms. On the basis of the magnetic structure obtained from neutron diffraction and theoretical calculations, we establish that these antisite defects cause the formation of FM nanoclusters with parallel alignment of Mn spin moments in a Mn2NiGa bulk lattice that has antiparallel Mn spin moments. The direction of the Mn moments in the soft FM cluster reverses with the external magnetic field. This causes a rotation or tilt in the antiparallel Mn moments at the cluster-lattice interface resulting in the observed asymmetry in magnetoresistance.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to AMER PHYSICAL SOC, USA
Department/Centre: Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Depositing User: Francis Jayakanth
Date Deposited: 04 Jan 2013 05:54
Last Modified: 04 Jan 2013 05:54
URI: http://eprints.iisc.ac.in/id/eprint/45617

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