Significant reduction in the thermal conductivity of Si-substituted Fe2VAl epilayers

Epitaxial Mn2VAl films with L21-ordered structure for all-Heusler stacks

“…(a) is caused by the Al-rich composition in the top-Mn 2 VAl layer.We have determined that epitaxial Mn 2 VAl films with a relatively high S L21 can be obtained by MBE at a low T g of 350 • C. It is noted that the values of S B2 and S L21 for the epitaxial Mn 2 VAl films in this study were almost equivalent to those for the epitaxial Fe 2 VAl films reported in our previous studies[39,40].Although there is only a difference in constituent elements at the (A,C) sites between L2 1 -Mn 2 VAl and L2 1 -Fe 2 VAl, the value of S B2 was ∼1 for both the Mn 2 VAl and Fe 2 VAl films. This indicates that the low-temperature MBE enables the suppression of Mn⇔V disordering or Fe⇔V disordering during growth.…”

“…During the growth of the trilayer, the substrate temperature was fixed to be 350 • C and we did not perform post-annealing after the growth of each layer. The detailed growth conditions for the Fe 2 VAl spacer layer are given in our previous studies [39,40,51]. After the growth of each layer, symmetrical streaks, which indicate two-dimensional epitaxial growth, were observed.…”

“…We have developed techniques for the growth of some full-Heusler alloys by low-temperature molecular beam epitaxy (MBE). Unlike most thin-film studies on full-Heusler alloys, relatively high degrees of structural ordering have been obtained at less than 350 • C [10,12,[33][34][35][36][37][38][39][40][41][42][43][44]. These low-temperature MBE techniques have also enabled all-Heusler stacks with sharp heterointerfaces [45,46].…”

Hard X‐Ray Photoemission Study of Heusler‐Type Fe2−xRexVAl Thermoelectric Compounds

“…Therefore, by optimizing the energy position of E F in the pseudo-gap, a significant increase in the Seebeck coefficient can be expected. Indeed, because of the sharp increase in the DOS on both sides of the pseudo-gap, the thermoelectric power of Fe 2 VAl compounds can be increased significantly by fourth-element doping [22][23][24][25][26][27][28][29][30][31][32][33][34] or off-stoichiometry. [35][36][37][38][39] According to previous reports, the Seebeck coefficient increases up to 70 μV/K for the p-type [23] and À130 μV/K for the n-type [22,26] by hole and electron doping, respectively.…”

Effective modelling of the Seebeck coefficient of Fe2VAl

“…However, their thermal conductivity, which is about ten times higher than Bi 2 Te 3 , results in a small thermoelectric figure of merit (ZT) [5,6]. The high thermal conductivity of Fe 2 VAl is phonon dominated and provides much room for improvement of ZT, hence several theoretical and experimental studies which aim to optimise the thermal conductivity (κ) as well as the Seebeck coefficient (S) and electrical conductivity (σ) have been conducted in the past two decades [2,3,[7][8][9][10][11][12].…”