Dresden 2014 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 55: Poster II

MA 55.90: Poster

Freitag, 4. April 2014, 10:30–13:30, P2

Zero Field ⁵⁵Mn NMR study of Ni-Mn-Sn Heusler alloys — •Maria Eleni Belesi¹, Ahmad Omar¹, Sabyasachi Pramanick², Subham Majumdar², Bernd Büchner^1,3, and Sabine Wurmehl^1,3 — ¹Leibniz Institute for Solid State and Materials Research, Dresden, Helmholtzstrasse 20, 01069 Dresden, Germany — ²Department of Solid State Physics, Indian Association for the Cultivation of Science, 2A and B Raja S. C. Mullick Road, Jadavpur, Kolkata 700 032, India — ³Institute for Solid State Physics, TU Dresden, D-01069, Germany

We present a nuclear magnetic resonance (NMR) study of the Heusler alloys Ni₂Mn_1+xSn_x, which are known to exhibit shape memory effects, exchange bias, inverse magnetocaloric and giant magnetoresistance in certain stoichiometry regimes. The x=0 member of the family, Ni₂MnSn, is a ferromagnetic Heusler alloy with a Curie temperature of T_C=349 K and cubic L2₁ structure. For 0.35<x<0.47 these compounds manifest a structural transition to the so-called martensitic phase, which has lower crystal symmetry than the parent cubic state and is dominated by a complex strained structure. To probe this structure as well as the accompanied modification of the local magnetic properties through the martensitic transition, we perform zero-field ⁵⁵Mn NMR experiments on Ni₂Mn_1+xSn_x samples prepared by arc melting. These experiments provide local information for the evolution of the structural and magnetic properties with stoichiometry and as we vary the temperature through the martensitic transition.