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MA: Fachverband Magnetismus

MA 4: Magnetic Heuslers, Half-metals and Oxides I (with TT)

MA 4.3: Vortrag

Montag, 31. März 2014, 10:00–10:15, BEY 118

Neutron diffraction study of Ni₄₅Co₅Mn₃₈Sb₁₂ Heusler system — •Roshnee Sahoo¹, Amitabh Das², KG Suresh¹, Daniel Ebke³, and Claudia Felser³ — ¹Department of Physics, Indian Institute of Technology Bombay, Mumbai-400076, India — ²Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai- 400085, India — ³Max Planck Institute of Chemical Physics of Solids, Dresden-01187, Germany

Considerably large martensitic transition temperature has been observed after substituting Co for Ni site in Ni₄₅Co₅Mn₃₈Sb₁₂ system. This system exhibits austenite L2₁ cubic structure with a=5.96 Å at high temperatures, while it has orthorhombic structure in the martensitic phase. We have carried out a detailed neutron diffraction study in order to establish the magnetic structure and the nature of magnetic coupling in this system. In Ni₄₅Co₅Mn₃₈Sb₁₂ system, from temperature variation of neutron diffraction data has shown that with increase in temperature the moments of 2a and 2f site decrease up to 250 K and after that both decrease. At 300 K, the material is in the austenite phase, which gives a moment of 1.1µ_B at 4a site and 0.8µ_B at 4b site. The fact that the spontaneous magnetization of 2µ_B is obtained from magnetization measurement suggests that the Mn moment at 4a and 4b sites are coupled ferromagnetically in austenite phase. It is also noticed that with increase in temperature the cell volume increases. However, near the martensitic transition there is a decrease of 0.3% of cell volume. Detailed structural and magnetic results, as obtained from the neutron data, will be discussed in the full paper.