Abstract
The specific heat of Mn3−xFexSi was measured over a wide temperature range. Aside from the lattice and electronic specific heat components, another component had a significant contribution to the specific heat at low temperatures in the case of x = 0.2; however, its contribution decreased when x = 1.0. It is observed that the net component was retained at temperatures significantly higher than TN for both x. The XAFS spectra of the Mn K-edge for x = 0 not only indicated a smooth structure near the edge, but also an unusually small amplitude in the extended high energy region; however, these features disappeared with Fe doping. The specific heat and XAFS data were discussed in terms of the charge degree of freedom or electronic inhomogeneity.
Highlights
The Heusler intermetallic compound Mn3Si [MnI(MnII)2Si] is an itinerant antiferromagnetic material, which exhibits an incommensurate spin-density-wave (SDW) order below T N = 21 K with two types of magnetic moments: μI ∼ 1.7μB and μII ∼ 0.2μB at the 4b (I site) and 8c (II site) sites, respectively, as presented in the Fm3m notation.[1]
This observation is in agreement with the spin sector data for Mn3Si obtained via NMR,[11] which indicates that a larger distribution in local magnetic fields at MnII compared with in MnI at low temperatures
The peak specific heat at T N might manifest the energy gap opening through Fermi-surface nesting, rather than a conventional antiferromagnetic phase transition of localized spins
Summary
Specific heat components; the large component could not be explained using antiferromagnetic spin waves.[3]. Pfleiderer et al noted that the Fermi-liquid theory would not be applicable to Mn3Si, rather, its magnetic-field insensitivity could be explained by attributing a half-metallic behavior to it.[3] the existence of a half-metallic band structure below T N was supported by first-principle calculations performed in a later study.[4] it is interesting to note that the insensitivity of Mn3Si to magnetic fields was observed even in the paramagnetic state, wherein the half-metallic band structure of Mn3Si should typically disappear. We measured the X-ray absorption fine structure (XAFS) of the Mn K-edge to deduce any relationship that might exist between Fe doping and the local structure and/or local valence state of Mn
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