Thermoelectric power of Ba(Fe_1−xCo_x)₂As₂ (0 ≤ x ≤ 0.05) and Ba(Fe_1−xRh_x)₂As₂ (0 ≤ x ≤ 0.171)

Abstract

Temperature-dependent, in-plane, thermoelectric power data are presented for single crystals of Ba(Fe_1−x Co _x )₂As₂ (0 ≤ x ≤ 0.05) and Ba(Fe_1−x Rh _x )₂As₂ (0 ≤ x ≤ 0.171). Given that previous thermoelectric power and angle resolved photoemission spectroscopy studies of Ba(Fe_1−x Co _x )₂As₂ delineated a rather large Co-concentration range for Lifshitz transitions to occur, and the underdoped side of the phase diagram is poorly explored, new measurements of thermoelectric power on tightly spaced concentrations of Co, 0 ≤ x ≤ 0.05, were carried out. The data suggest evidence of a Lifshitz transition, but instead of a discontinuous jump in thermoelectric power in the range 0 ≤ x ≤ 0.05, a more gradual evolution in the S(T) plots as x is increased was observed. The thermoelectric power data of Ba(Fe_1−x Rh _x )₂As₂ show very similar behavior to that of Co substituted BaFe₂As₂. The previously outlined T–x phase diagrams for both systems are further confirmed by these thermoelectric power data.

Keywords:

• thermoelectric power
• TEP

Acknowledgments

The authors would like to thank: W.E. Straszheim for the elemental analysis of the single crystals; M.A. Tanatar for soldering Sn to the ends of the sample; and A. Jesche, X. Lin, and V. Taufour as well as the five Kims: H, M, R, S and -chi for valuable discussions. German D. Samolyuk is thanked as well for suggestions for refinement of measurement procedures. This work was done at Ames Laboratory, US DOE, under contract #DE-AC02-07CH111358. This work was supported by the US Department of Energy, Office of Basic Energy Science, Division of Materials Sciences and Engineering. S.L.B. and P.C.C. were supported in part by the State of Iowa through the Iowa State University.

Notes

Currently: Marie Curie Fellow at Los Alamos National Laboratory.

Additional information

Notes on contributors

Ni Ni

Currently: Marie Curie Fellow at Los Alamos National Laboratory.