The model strongly correlated electron system ${\mathrm{Ho}}_{0.8}{\mathrm{Lu}}_{0.2}{\mathrm{B}}_{12}$, which demonstrates a cooperative Jahn-Teller instability of the boron sublattice in combination with rattling modes of Ho(Lu) ions, dynamic charge stripes, and an unusual antiferromagnetic (AF) ground state, has been studied in detail at low temperatures by magnetoresistance (Δρ/ρ), magnetization, and heat capacity measurements. Based on received results it turns out that the angular H-φ-T magnetic phase diagrams of this nonequilibrium AF metal can be reconstructed in the form of a “Maltese cross”. The dramatic AF ground state symmetry lowering of this dodecaboride with fcc crystal structure can be attributed to the redistribution of conduction electrons. These leave the Ruderman-Kittel-Kasuya-Yosida oscillations of the electron spin density to participate in the dynamic charge stripes providing extraordinary changes in the indirect exchange interaction between magnetic moments of $\mathrm{H}{\mathrm{o}}^{3+}$ ions and resulting in the emergence of a number of various magnetic phases. It is also shown that the two main contributions to magnetoresistance in the complex AF phase, the (i) positive linear on magnetic field and the (ii) negative quadratic $-\mathrm{\Delta }\rho /\rho \sim H^2$ component can be separated and analyzed quantitatively, correspondingly, in terms of charge carrier scattering on the spin density wave ($5d$) component of the magnetic structure and on local $4f-5d$ spin fluctuations of holmium sites.

• Received 7 March 2019

DOI:https://doi.org/10.1103/PhysRevB.99.174430