Tensile and compressive strain tuning of a Kondo lattice

We present electrical resistivity measurements on the prototypical heavy-fermion metal YbRh₂Si₂ (YRS) under a-axis tensile and compressive strain and focus on the evolution of the resistivity maximum near 136 K that arises from the interplay of the Kondo effect and the crystal electric field (CEF) splitting. While compressive strain reduces Tₘₐₓ, similar as previously reported for hydrostatic pressure, Tₘₐₓ is enhanced up to 145 K for 0.13% tensile strain. Model calculations for the strain effect on CEF splitting in YRS reveal a negligible shift of the levels. Instead, the enhancement of the resistivity maximum indicates a 20% increase of the Kondo temperature. This opens the perspective to access the hidden zero-field quantum critical point in pure YRS.