First-order transition from a Kondo insulator to a ferromagnetic metal in single crystalline FeSi(1-x)Ge(x).
The phase diagram of FeSi(1-x)Ge(x), obtained from magnetic, thermal, and transport measurements on single crystals, shows a discontinuous transition from Kondo insulator to ferromagnetic metal with x at a critical concentration, x(c) approximately 0.25. The gap of the insulating phase strongly decreases with x. The specific heat gamma coefficient appears to track the density of states of a Kondo insulator. The phase diagram is consistent with an insulator-metal transition induced by a reduction of the hybridization with x in conjunction with disorder on the Si/Ge ligand site.
Yeo
S
S
National High Magnetic Field Laboratory (NHMFL), Tallahassee, Florida 32310, USA.
Nakatsuji
S
S
Bianchi
A D
AD
Schlottmann
P
P
Fisk
Z
Z
Balicas
L
L
Stampe
P A
PA
Kennedy
R J
RJ