Frustrated Kondo chains and glassy magnetic phases on the pyrochlore lattice

Abstract

We present an extensive numerical study of a new type of frustrated itinerant magnetism on the pyrochlore lattice. In this theory, the pyrochlore magnet can be viewed as a cross-linking network of Kondo or double-exchange chains. Contrary to models based on Mott insulators, this itinerant magnetism approach provides a natural explanation for several spin and orbital superstructures observed on the pyrochlore lattice. Through extensive Monte Carlo simulations, we obtain the phase diagrams at two representative electron filling fractions $n=1/2$ and 2/3. In particular, we show that an intriguing glassy magnetic state characterized by ordering wavevectors $\mathbf{q}=\left(\frac{1}{3},\frac{1}{3},1\right)$ gives a rather satisfactory description of the low temperature phase recently observed in spinel GeFe${}_2$O${}_4$.

10 pages, 12 figures