Strong electron correlations in FeSb₂

Abstract

FeSb2 has been recently identified as a new model system for studying many‐body renormalizations in a d‐electron based narrow gap semiconducting system, strongly resembling FeSi. The electron‐electron correlations in FeSb2 manifest themselves in a wide variety of physical properties including electrical and thermal transport, optical conductivity, magnetic susceptibility, specific heat and so on. We review some of the properties that form a set of experimental evidences revealing a significant role of correlation effects in FeSb2. The metallic state derived from slight Te doping in FeSb2, which exhibits a large quasiparticle mass, will also be introduced.

Highly dispersive electron relaxation and colossal thermoelectricity in the correlated semiconductor FeSb2

“…With the origin of the enhanced TEP of FeSi in debate for decades [7][8][9], the observations in FeSb 2 , with the thermoelectric power factor the largest ever reported [3,10,11], have added timely interest to this concern. Accumulating experimental facts have confirmed the significant effect of electronelectron correlations in FeSb 2 [3][4][5][6][10][11][12][13][14][15][16][17]. These include the large spectral weight redistribution up to higher energies [14,15] and the occurrence of electronic Griffiths phases at low temperatures [17].…”

“…FeSb 2 is a new, d-electron based correlated semiconductor closely resembling FeSi [4][5][6]. With the origin of the enhanced TEP of FeSi in debate for decades [7][8][9], the observations in FeSb 2 , with the thermoelectric power factor the largest ever reported [3,10,11], have added timely interest to this concern.…”

Phonon-drag effect inFeGa3

“…This feature has been argued to arise due to the presence of strong electronic correlations in these two systems. 6,45 Though no static magnetic ordering has been observed in pure FeGa 3 until now, weak ferromagnetic order has been observed 25 for the Ge-doped FeGa 3−x Ge x with x = 0.13 and weakly coupled local moments have been observed for Co-doped Fe 1−x Co x Ga 3 with x = 0.05. 46 These attributes in FeGa 3 are also similar to FeSi and FeSb 2 where no static magnetic order is observed in the pure compounds, but ferromagnetic metallic states are discerned in FeSi 0.75 Ge 0.25 , FeSb 2−x Te x and Fe 1−x Co x Sb 2 .…”

Electronic Griffiths Phase in the Te-Doped SemiconductorFeSb2

“…Even more disorder tunes the system again to an insulating state due to localization effects [11,38]. Whereas the EGP formalism has been developed for disordered Kondo systems, we note that the Hubbard U in the strongly correlated electronic system of is FeSb 2 is reduced from the values common in lanthanide based heavy fermions and Fe moments are not as localized [39][40][41]. Nevertheless, the EGP predictions are in qualitative agreement with the Fe(Sb 1−x Te x ) 2 phase diagram [22] and with the values we obtained in Table I.…”