Electronic landscape of the f -electron intermetallics with the ThCr ₂ Si ₂ structure

Abstract

Although strongly correlated f -electron systems are well known as reservoirs for quantum phenomena, a persistent challenge is to design specific states. What is often missing are simple ways to determine whether a given compound can be expected to exhibit certain behaviors and what tuning vector(s) would be useful to select the ground state. In this review, we address this question by aggregating information about Ce, Eu, Yb, and U compounds with the ThCr 2 Si 2 structure. We construct electronic/magnetic state maps that are parameterized in terms of unit cell volumes and d -shell filling, which reveals useful trends including that (i) the magnetic and nonmagnetic examples are well separated, and (ii) the crossover regions harbor the examples with exotic states. These insights are used to propose structural/chemical regions of interest in these and related materials, with the goal of accelerating discovery of the next generation of f -electron quantum materials.

Observation of Kondo lattice and Kondo-enhanced anomalous Hall effect in an itinerant ferromagnet

“…As f-valence is extremely sensitive to external perturbations due to vanishing bandwidth, further transport experiments on CeCo 2 As 2 with hydrostatic pressure 6 and strong magnetic field 10 would be particularly interesting, where unconventional superconductivity may arise along with the breakdown of Kondo lattice or ferromagnetism 24,25 . We anticipate a low pressure will be needed to drive the phase transition since CeCo 2 As 2 has been recently predicted to be at the boundary between trivalent and tetravalent Cerium valence state in the global phase diagram 46 . Our findings open a new avenue for realizing high-temperature ferromagnetic Kondo lattices and also provide a general guideline for searching for topological quantum phenomena in the heavy-fermion magnets, especially the compounds sharing similar structure with 45,46 .…”

“…We anticipate a low pressure will be needed to drive the phase transition since CeCo 2 As 2 has been recently predicted to be at the boundary between trivalent and tetravalent Cerium valence state in the global phase diagram 46 . Our findings open a new avenue for realizing high-temperature ferromagnetic Kondo lattices and also provide a general guideline for searching for topological quantum phenomena in the heavy-fermion magnets, especially the compounds sharing similar structure with 45,46 . We choose CoAs flux instead of bismuth 10 in order to avoid the remnant Bi flux which strongly modifies the transport properties (Fig.…”

On the Ytterbium Valence and the Physical Properties in Selected Intermetallic Phases

“…Purely divalent ytterbium compounds have the valence electron configuration 4f 14 , which exhibits high stability. This filled 4f shell can be considered as a core-electron shell; therefore, no magnetic moment is observed.…”

Development of a Geometric Descriptor for the Strategic Synthesis of Remeika Phases

“…Such observations open the question of whether we can enhance the tunability of intermetallic compounds by better understanding the factors dictating stability. Our group and others now seek to predict and synthesize new quantum materials by considering subunits 73 and geometric factors as a strategic first step. In the past decade, it has been demonstrated that several compounds adopting the Remeika phases show superconductivity and charge density waves.…”

“…Our group and others now seek to predict and synthesize new quantum materials by considering subunits and geometric factors as a strategic first step. In the past decade, it has been demonstrated that several compounds adopting the Remeika phases show superconductivity and charge density waves.…”