Muon-spin-relaxation and inelastic neutron scattering investigations of the caged-type Kondo semimetals: CeT₂Al₁₀(T = Fe, Ru and Os)

Abstract

Recently the Ce-based caged-type compounds having general formula CeT2Al10\n(T=Fe, Ru and Os) have generated considerable interest due to the Kondo\nsemiconducting paramagnetic ground state (down to 40 mK) observed in CeFe2Al10\nand anomalously high magnetic ordering temperature with a spin gap formation at\nlow temperatures in Kondo semimetals CeRu2Al10 and CeOs2Al10. The formation of\nlong-range magnetic ordering out of the Kondo semiconducting/semimetallic state\nitself is extraordinary and these are the first examples of this enigmatic\ncoexistence of electronic ground states. These compounds also exhibit strong\nanisotropy in the magnetic and transport properties, which has been explained\non the basis of single ion crystal electric field (CEF) anisotropy in the\npresence of strongly anisotropic hybridization between localised 4f-electron\nand conduction electrons. Further they also exhibit a remarkable modification\nof magnetic and transport properties with doping on Ce, or T or Al sites. In\nthis review we briefly discuss the bulk properties of these compounds, giving a\ndetailed discussion on our muon-spin-relaxation (muSR) investigations and\ninelastic neutron scattering (INS) results.\n