Abstract
Frustrated interactions exist throughout nature, with examples ranging from protein folding through to frustrated magnetic interactions. Whilst magnetic frustration is observed in numerous electrically insulating systems, in metals it is a rare phenomenon. The interplay of itinerant conduction electrons mediating interactions between localised magnetic moments with strong spin-orbit coupling is likely fundamental to these systems. Therefore, knowledge of the precise shape and topology of the Fermi surface is important in any explanation of the magnetic behaviour. PdCrO2, a frustrated metallic magnet, offers the opportunity to examine the relationship between magnetic frustration, short-range magnetic order and Fermi surface topology. By mapping the short-range order in reciprocal space and experimentally determining the electronic structure, we have identified the dual role played by the Cr electrons in which the itinerant ones on the nested paramagnetic Fermi surface mediate the frustrated magnetic interactions between local moments.
Highlights
Allowed the validation of the calculated electronic structure from which it is shown that the Fermi surface of this system has a propensity for nesting at a wave-vector that is concomitant with the observed short-range magnetic order above the ordering temperature and subsequent magnetic ordering below
By resolving the crystal momentum-dependence of the nesting instability, we have shown exactly which conduction electrons are responsible for mediating the frustrated magnetic interactions, culminating in the observed magnetic order
The diffuse scattering is quite broad in the hk-plane and extends in rods along l, implying that the magnetic correlations are two-dimensional in nature
Summary
Allowed the validation of the calculated electronic structure from which it is shown that the Fermi surface of this system has a propensity for nesting at a wave-vector that is concomitant with the observed short-range magnetic order above the ordering temperature and subsequent magnetic ordering below. An unconventional anomalous Hall effect has been seen in this compound at temperatures lower than T* = 20 K22 and it has recently been reported that a tilting of the 120° spin planes in different Cr layers gives rise to a finite scalar spin chirality which, in the presence of a net magnetisation from an applied magnetic field, may be responsible for the observed effect[14,23] These results indicate substantial coupling between the localised spins within the Cr layers and the conduction electrons in the Pd layer[15,21]. There has been a focus on the magnetically ordered phase of PdCrO213,14,18–22, much less attention has been paid to the paramagnetic state and, in particular, the region just above TN
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