Analysis of Temperature (T) and Resistance (R) data of Ce_1-xPr_xOs₄Sb₁₂ (0≤ x ≤ 0.25)

Filled Skutterudite structures follow the chemical formula of MT₄X₁₂ where M is an alkali metal, alkaline-earth metal, lanthanide, or actinide, T is typically Fe, Ru, or Os, while X is P, As, or Sb. The specific compound we’re investigating is Ce_1-xPr_xOs₄Sb₁₂ (x = 0.15, 0.25), which is of interest due to its unique semimetal properties dependent on temperature (T) and applied magnetic field (H). Yet, CeOs₄Sb₁₂ was previously thought to be a Kondo insulator due to its resistance (R) and T decreasing until a resistance minimum (R_min), then the R increases again, reminiscent of semiconducting behavior. However, when a magnetic field beyond 2 tesla is applied, the low temperature resistance reaches a maximum (R_max) and begins to drop. These features produce an unusual reverse wedge-shaped T-vs-H phase boundary related to a valence transition in CeOs₄Sb₁₂ that has been established [1,2]. Resistance measurements taken by the previous undergraduate student on the study of Pr substitution of Ce in Ce_1-xPr_xOs₄Sb₁₂ (x = 0.1, 0.2) showed an increasing Pr concentrations shift of R_min to lower temperatures [3]. In this work, we perform resistance R(T) measurements on samples with x = 0.15 and 0.25 to extend and complete the low-Pr substitution study (single crystals were synthesized in Prof. Maple’s facility at UCSD).

REF [1] K. Götze et. al, New J. Phys. 24, 043044 (2022); PRB 101, 075102 (2020). [2] P.-C. Ho et. al, PRB 94, 205140 (2016). [3] L. M. Ramos et. al, 2023 APS March Meeting, Abstract # A30.00006 (2023).