116 research outputs found
Mechanism of magnetostructural transformation in multifunctional MnGaC
MnGaC undergoes a ferromagnetic to antiferromagnetic, volume
discontinuous cubic-cubic phase transition as a function of temperature,
pressure and magnetic field. Through a series of temperature dependent x-ray
absorption fine structure spectroscopy experiments at the Mn K and Ga K edge,
it is shown that the first order magnetic transformation in MnGaC is
entirely due to distortions in Mn sub-lattice and with a very little role for
Mn-C interactions. The distortion in Mn sub-lattice results in long and short
Mn-Mn bonds with the longer Mn-Mn bonds favoring ferromagnetic interactions and
the shorter Mn-Mn bonds favoring antiferromagnetic interactions. At the first
order transition, the shorter Mn-Mn bonds exhibit an abrupt decrease in their
length resulting in an antiferromagnetic ground state and a strained lattice.Comment: Accepted in J. Appl. Phys. Please contact authors for supplementary
informatio
Resistivity and Thermopower of Ni2.19Mn0.81Ga
In this paper, we report results of the first studies on the thermoelectric
power (TEP) of the magnetic heusler alloy NiMnGa. We explain
the observed temperature dependence of the TEP in terms of the crystal field
(CF) splitting and compare the observed behavior to that of the stoichiometric
system NiMnGa. The resistivity as a function of temperature of the two
systems serves to define the structural transition temperature, T, which is
the transition from the high temperature austenitic phase to low temperatures
the martensitic phase. Occurrence of magnetic (Curie-Weiss) and the martensitic
transition at almost the same temperature in NiMnGa has been
explained from TEP to be due to changes in the density of states (DOS) at the
Fermi level.Comment: 12 pages, 4 figures, Accepted in Physical Review B vol 70, Issue 1
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