Transport Properties of Heusler Compounds Fe_3-xV_xAl

Abstract

The electrical resistivity and thermopower S of Heusler compounds Fe 3Àx V x Al have been measured at the temperature range from 1.5 to 300 K at magnetic fields up to 15 T. The measurements of and S in the high temperature range up to 800 K have been performed. and S show a semiconducting behavior at high temperatures, and the obtained experimental energy gap increases almost linearly with increasing V concentration x. S is positive for x < 1:0 and negative for x ! 1:0 at all measured temperatures, indicating a drastic change of major carriers at x ¼ 1:0. The electron scattering due to the magnetic fluctuations of Fe clusters has a dominant effect on the behavior of of the magnetic compounds at low temperatures. On the other hand, S is not sensitive to the magnetic state and the external magnetic field, which is related to the energy dependence of magnetic scattering at the Fermi level.

Angle-Resolved Photoemission Analysis of Electronic Structures for Thermoelectric Properties of Off-Stoichiometric Fe_2–xV_1+xAl Alloys

“…In Fe/V off-stoichiometric Fe 2-x V 1+x Al [17][18][19][20][21] , however, the dependence of thermoelectric power S on excess V content x cannot even be qualitatively explained in terms of the rigid-band model, as shown by the open circles in Fig. 2.…”

Thermoelectric performance and the role of anti-site disorder in the 24-electron Heusler TiFe2Sn

“…[13,14] VFe 2 Al displays a large Seebeck coefficient (|S| > 150 µV/K) upon varying the VEC slightly from 24, achieved by introducing Ge [15] or Si [16] to the Al site, varying the V-Al ratio, [17,18,19] and varying the Fe-V ratio. [20,21] In contrast to VFe 2 Al, TiFe 2 Sn is a less explored compound, and the existing literature on TiFe 2 Sn has not indicated significant improvements in Seebeck coefficient upon varying the Ti:Fe ratio. [22,23] This discrepancy between calculations and experimental results is likely the result of anti-site Ti/Fe disorder, as has been suggested by lab X-ray diffraction and Mössbauer studies.…”

Weak itinerant ferromagnetism in Heusler-typeFe2VAl0.95

“…6 Stoichiometric Fe 2 VAl is nonmagnetic and related alloys, such as Fe 2+x V 1−x Al and Fe 2 VAl 1−␦ , exhibit ferromagnetic transitions. 7,[10][11][12][13][14] Consequently, the samples at x Ϸ 0 and ␦ Ϸ 0 are located at the brink of ferromagnetic order, close to the ferromagnetic quantum critical point, i.e., T C → 0. 6,8 Stimulated by these findings, theoretical work claimed Fe 2 VAl is a nonmagnetic semimetal with the pseudogap at the Fermi level.…”