Charge-Doping-Driven Evolution of Magnetism and Non-Fermi-Liquid Behavior in the Filled SkutteruditeCePt4Ge12−xSbx

Abstract

The filled skutterudite compound CePt(4)Ge(12) is situated close to the border between the intermediate valence of Ce and heavy-fermion behavior. Substitution of Ge by Sb drives the system into a strongly correlated and, ultimately, upon further increasing the Sb concentration, an antiferromagnetically ordered state. Our experiments evidence a delicate interplay of emerging Kondo physics and the formation of a local 4f moment. An extended non-Fermi-liquid region, which can be understood in the framework of a Kondo-disorder model, is observed. Band-structure calculations support the conclusion that the physical properties are governed by the interplay of electron supply via Sb substitution and the concomitant volume effects.

Probing strong Kondo disorder with measurements of thermoelectric power

“…These regions correspond to the ground states reported in Ref. [16] and indicate significant redistributions of spectral weight associated with the many-body and Kondo resonances upon crossing their boundaries. At low T and for 0.84 ≤ x ≤ 1.5, S(T )/T appears to diverge with decreasing T with a NFL form, S(T )/T ∼ 1/T S log(T S /T ), where T S = T γ , in general.…”

“…Chemical substitution of Sb for Ge in the system CePt 4 Ge 12−x Sb x produces strongly-disordered hybridization which tunes the system through a region of NFL behavior for 1 ≤ x ≤ 1.3, and leads to antiferromagnetic (AFM) order for x ≥ 1.9 [16]. In this letter, we demonstrate how sensitively measurements of S(T ) probe Kondo disorder in CePt 4 Ge 12−x Sb x .…”

“…The compound CePt 4 Ge 12 has a FL ground state [15][16][17] with no ordered phase down to 50 mK [16]. Chemical substitution of Sb for Ge in the system CePt 4 Ge 12−x Sb x produces strongly-disordered hybridization which tunes the system through a region of NFL behavior for 1 ≤ x ≤ 1.3, and leads to antiferromagnetic (AFM) order for x ≥ 1.9 [16].…”

A large family of filled skutterudites stabilized by electron count

“…Filled skutterudites based on rare-earth metals and group 8 transition elements show diverse and interesting rare-earth magnetism, and they have been widely studied (see, for example, refs 28,29,31). To generally survey the magnetic properties for our new filled group 9-based skutterudites, the magnetizations of all the rare-earth-based filled skutterudites were measured from 2 to 200 K with an applied magnetic field of m 0 H ¼ 1 Tesla.…”

“…Because they make very good thermoelectrics 21,22,47 , host unusual metalinsulator transitions [23][24][25] , can be rare-earth magnets, heavyfermion compounds [26][27][28][29][30] , non-Fermi liquids [31][32][33][34][35] , itinerant ferromagnets [36][37][38] and superconductors 27,[39][40][41][42][43][44][45][46] , and have been proposed as topological insulators 48 , filled skutterudites are a very important class of non-molecular solids. Because the electronic and magnetic properties of solids depend critically on the actual atoms making up the compounds in addition to the compound's electron count, expanding the filled skutterudites from primarily group 8 to group 9 metal-based compounds, as we have done in this study, affords the opportunity to observe many new physical properties.…”