Using first-principles calculations to screen for fragile magnetism: Case study of LaCrGe3 and LaCrSb3

Abstract

In this paper, we present a coupled experimental/theoretical investigation of pressure effect on the ferromagnetism of LaCrGe3 and LaCrSb3 compounds. The magnetic, electronic, elastic, and mechanical properties of LaCrGe3 and LaCrSb3 at ambient condition are studied by first-principles density-functional theory calculations. The pressure dependences of the magnetic properties of LaCrGe3 and LaCrSb3 are also investigated. The ferromagnetism in LaCrGe3 is rather fragile, with a ferro-to paramagnetic transition at a relatively small pressure (around 7 GPa from our calculations, and 2 GPa in experiments). The key parameter controlling the magnetic properties of LaCrGe3 is found to be the proximity of the peak of Cr density of states to the Fermi level, a proximity that is strongly correlated with the distance between Cr atoms along the c axis, suggesting that there would be a simple way to suppress magnetism in systems with one-dimensional arrangement of magnetic atoms. By contrast, the ferromagnetism in LaCrSb3 is not fragile. Our theoretical results are consistent with our experimental results and demonstrate the feasibility of using first-principles calculations to aid experimental explorations in screening for materials with fragile magnetism. In this paper, we present a coupled experimental/theoretical investigation of pressure effect on the ferromagnetism of LaCrGe 3 and LaCrSb 3 compounds. The magnetic, electronic, elastic, and mechanical properties of LaCrGe 3 and LaCrSb 3 at ambient condition are studied by first-principles density-functional theory calculations. The pressure dependences of the magnetic properties of LaCrGe 3 and LaCrSb 3 are also investigated. The ferromagnetism in LaCrGe 3 is rather fragile, with a ferro-to paramagnetic transition at a relatively small pressure (around 7 GPa from our calculations, and 2 GPa in experiments). The key parameter controlling the magnetic properties of LaCrGe 3 is found to be the proximity of the peak of Cr density of states to the Fermi level, a proximity that is strongly correlated with the distance between Cr atoms along the c axis, suggesting that there would be a simple way to suppress magnetism in systems with one-dimensional arrangement of magnetic atoms. By contrast, the ferromagnetism in LaCrSb 3 is not fragile. Our theoretical results are consistent with our experimental results and demonstrate the feasibility of using first-principles calculations to aid experimental explorations in screening for materials with fragile magnetism. Disciplines Condensed Matter Physics | Materials Science and Engineering | Physics

Magnetic Properties of the Hexagonal Ferromagnet NdCrGe3 Showing Metamagnetic Transition and Negative Magnetocaloric Effect

“…The systems with the space group of P 6 3 / mmc , such as the Ising ferromagnet FeCr 2 Te 4 , the topological superconductor BaSn 3 , and the ferromagnetic nodal-line semimetal candidate Fe 3 GeTe 2 , have recently attracted essential interest, presumably due to the special crystalline symmetry, , which makes these systems promising topological nontrivial materials and worthy of both theoretical and experimental investigation. , Furthermore, the structure of NdCrGe 3 consists of chains of face-sharing Cr-centered octahedra, 1 ∞ [CrGe 6/2 ], aligned along the c axis, separated by Nd atoms. The chains expand infinitely along the c direction [Figure (a,b)], exhibiting 1D features. , The Nd atoms are coordinated by 12 Ge atoms in an anticuboctahedral geometry. , Owing to the 1D crystal structure and the P 6 3 / mmc space group, NdCrGe 3 should be a potentially fruitful system in further theoretical and experimental research. − Previously, the single crystals of LnCrGe 3 (Ln = rear earths), which were as tiny as 0.5 mm, were fabricated, and the basic magnetic properties were measured but based on polycrystalline samples . We have investigated the critical behavior and magnetocaloric of PrCrGe 3 single crystal around the ferromagnetic transition…”

Magnetic properties of the itinerant ferromagnet LaCrGe3 under pressure studied by La139 NMR

“…3(b) and 4(b) was determined by the measurements with modified Bridgman pressure cells which may produce larger pressure gradients compared with piston-cylinder pressure cells. The ferromagnetic instability in LaCrGe 3 has been shown to be primarily driven by the Cr-Cr distance along the c axis [33], which would be the direction of higher pressure gradients in the previous measurements in Bridgman cells [24,32]. Therefore the results of the NMR measurements by utilizing the piston-cylinder pressure cells should be compared with the phase diagram of Fig.…”

Mechanism for transitions between ferromagnetic and antiferromagnetic orders in d-electron metallic magnets

“…Face-sharing octahedra of Ge atoms encompassing Cr in LaCrGe 3 imply that correlated 3 d -states not only hybridize to p -ones of surrounding ligands but also bond between each other 23 , justifying a general p - d orbital structure of the model (1). In turn, parametrization of the model can be extracted from the electronic properties of LaCrGe 3 ( i ) shallow d -level position 23,24 and 3 d nature of Cr valence states indicate U /| ε d | ≫ 1; ( ii ) general agreement with (La 3+ )(Cr 3+ )(Ge 2− ) 3 oxidation state 23 pinpoints n d < 1; ( iii ) bonding between 3 d -states twice smaller than their hybridization to p -states 23 suggests 2| t d | ≃ | V |.…”