Electronic structure of LuRh2Si2: ‘small’ Fermi surface reference to YbRh2Si2

Abstract

We present band structure calculations and quantum oscillation measurements on LuRh _2 Si _2 , which is an ideal reference to the intensively studied quantum critical heavy-fermion system YbRh _2 Si _2 . Our band structure calculations show a strong sensitivity of the Fermi surface on the position of the silicon atoms z _Si within the unit cell. Single crystal structure refinement and comparison of predicted and observed quantum oscillation frequencies and masses yield z _Si = 0.379 c in good agreement with numerical lattice relaxation. This value of z _Si is suggested for future band structure calculations on LuRh _2 Si _2 and YbRh _2 Si _2 . LuRh _2 Si _2 with a full f electron shell represents the ‘small’ Fermi surface configuration of YbRh _2 Si _2 . Our experimentally and ab intio derived quantum oscillation frequencies of LuRh _2 Si _2 differ significantly from the results of earlier measurements on YbRh _2 Si _2 . Consequently, our results confirm the contribution of the f electrons to the Fermi surface of YbRh _2 Si _2 at high magnetic fields. Yet, the limited agreement with refined fully itinerant local density approximation calculations highlights the need for more elaborate models to describe the Fermi surface of YbRh _2 Si _2 .