Correlated Magnetic Weyl Semimetal State in Strained Pr₂Ir₂O₇

Abstract

Correlated topological phases (CTPs) with interplay between topology and electronic correlations have attracted tremendous interest in condensed matter physics. Therein, correlated Weyl semimetals (WSMs) are rare in nature and, thus, have so far been less investigated experimentally. In particular, the experimental realization of the interacting WSM state with logarithmic Fermi velocity renormalization has not been achieved yet. Here, experimental evidence of a correlated magnetic WSM state with logarithmic renormalization in strained pyrochlore iridate Pr2Ir2O7 (PIO) which is a paramagnetic Luttinger semimetal in bulk, is reported. Benefitting from epitaxial strain, “bulk‐absent” all‐in–all‐out antiferromagnetic ordering can be stabilized in PIO film, which breaks time‐reversal symmetry and leads to a magnetic WSM state. With further analysis of the experimental data and renormalization group calculations, an interacting Weyl liquid state with logarithmically renormalized Fermi velocity, similar to that in graphene, is found, dressed by long‐range Coulomb interactions. This work highlights the interplay of strain, magnetism, and topology with electronic correlations, and paves the way for strain‐engineering of CTPs in pyrochlore iridates.

Higher harmonics in planar Hall effect induced by cluster magnetic multipoles

“…At 30 K, the second harmonic always exists, which is induced by the cluster dipole. The additional higher harmonics appear below 30 K. The appearance of the fourth harmonic in the ( ϕ ) oscillation has been attributed to the A 2 -CMO-induced chiral anomaly in Pr 2 Ir 2 O 7 thin films 41 . Considering that both Pr 2 Ir 2 O 7 and NIO-227 films have the A 2 -CMO, the observed fourth harmonic of the ( ϕ ) oscillation in the NIO-227 film should originate from the A 2 -CMO.…”

“…Figure 4c shows the fitting results for at a selected temperature of ~ 4 K with (red line) and without (black dashed line) the H 3 and H 4 terms. Note that the exact proportions of dipole and CMOs cannot be determined by experimental PHE due to the complexity behind transport phenomena 41 , but we can get it theoretically (Supplementary Fig. 11 ).…”

“…The associated PHE in both ferromagnets and Weyl semimetals exhibit sin (2 ϕ ) or second harmonic PHE oscillations. In contrast, higher harmonics PHE oscillations beyond second in topological systems 41 – 44 have been recently reported, in which higher harmonics PHE originated from additional unknown parameters in materials.…”

Recent Progress on Titanium Sesquioxide: Fabrication, Properties, and Applications

“…Thus, the on-site Coulomb interaction (U) must be considered between the Ti 3d 1 electrons, and this interaction creates a bandgap in α-Ti 2 O 3 (Figure 3e). [39,46,47] Mott, Hubbard, and coworkers developed a theoretical model for strongly correlated systems, which yields interesting physical properties including high-temperature superconductivity, [68][69][70][71][72][73] MIT, [74][75][76][77] colossal magnetoresistance, [78][79][80] and correlated topological phases, [81][82][83] among others.…”

Ultra-flat and long-lived plasmons in a strongly correlated oxide

“…Depending on the difference between U and the charge-transfer energy ( Δ ), strongly correlated oxides are classified as either charge-transfer insulators ( U > Δ ) or Mott insulators ( U < Δ ). Several fascinating properties have been observed in strongly correlated oxides, including correlated topological phases 7 , 8 , metal-insulator transitions (MIT) 3 , and unconventional superconductivity 9 , among others. As collective motions of electrons, plasmons arise from long-range Coulomb interaction.…”