The Complex Magnetism in the Breathing Pyrochlore LiIn(Cr_1-xRh_x)_4O_8

We perform a detailed investigation of the new 'breathing' pyrochlore compound LiInCr_4O_8 through Rh substitution with measurements of magnetic susceptibility, specific heat, and x-ray powder diffraction. The antiferromagnetic phase of LiInCr_4O_8 is found to be slowly suppressed with increasing Rh, up to the critical concentration of x=0.1 where the antiferromagnetic phase is still observed with the peak in specific heat T_\rm p=12.5 K, slightly lower than T_\rm p=14.3 K for the x=0 compound. From the measurements of magnetization we also uncover evidence that substitution increases the amount of frustration. Comparisons are made with the LiGa_yIn_1-yCr_4O_8 system as well as other frustrated pyrochlore-related materials and comparable amounts of frustration are found. The results of this work show that the engineered breathing pyrochlores present an important method to further understand the complex magnetism in frustrated systems.