FIG 9 - uploaded by Nandini Trivedi
Content may be subject to copyright.
Source publication
Triple points, triply degenerate band crossings, have been recently identified as a new type of fermion realized in electronic systems. We present a bosonic analog of a triple point topological semimetal. We theoretically show that such triple points can arise in the magnon band structure of pyrochlore iridates with the all-in-all-out antiferromagn...
Context in source publication
Citations
... 21 As a result there have been many intriguing proposals to use magnetic excitations as a platform for realizing analogs of other topological systems. Recent examples include analogs of the Haldane-Kane-Mele model, 22 Dirac semimetals, 23,24 Weyl semimetals, 25,26 triple points, 27 and chiral topological insulators. 28 The most studied class of systems, however, is ordered magnetic insulators with topological magnon bands, associated with nonzero Chern numbers. ...
... 40,41 Of particular interest is noncoplanar orders where a finite scalar spin chirality 13 S i · S j × S k can produce the non-trivial topology. 42 This is the reason why several theoretical predictions focus on intrinsically non-coplanar magnetic configurations such as in pyrochlore iridate thin films, 43 and bulk systems, 27 , or noncollinear configurations canted out-of-plane by a magnetic field. For the latter case, the magnon thermal Hall effect has been predicted on the star, 42 honeycomb, 44 and kagome lattices. ...
... The predicted values are on the same or better order as experimental observations for the magnon thermal Hall effect, [14][15][16]18 and predicted values for pyrochlore iridates in the noncollinear all-in-all-out spin configuration. 27 We next explore regions of higher canting, where stronger effects are expected. 42,45,58 Recalling the effective field Eq. (15), we achieve this by tuning the applied transverse field, or the in-plane DMI strength. ...
We theoretically study magnetic and topological properties of antiferromagnetic kagome spin systems in the presence of both in- and out-of-plane Dzyaloshinskii-Moriya interactions. In materials such as the iron jarosites, the in-plane interactions stabilize a canted noncollinear “umbrella” magnetic configuration with finite scalar spin chirality. We derive expressions for the canting angle and use the resulting order as a starting point for a spin-wave analysis. We find topological magnon bands, characterized by nonzero Chern numbers. We calculate the magnon thermal Hall conductivity and propose the iron jarosites as a promising candidate system for observing the magnon thermal Hall effect in a noncollinear spin configuration. We also show that the thermal conductivity can be tuned by varying an applied magnetic field or the in-plane Dzyaloshinskii-Moriya strength. In contrast to previous studies of topological magnon bands, the effect is found to be large even in the limit of small canting.
... 21 As a result there have been many intriguing proposals to use magnetic excitations as a platform for realizing analogs of other topological systems. Recent examples include analogs of the Haldane-Kane-Mele model, 22 Dirac semimetals, 23,24 Weyl semimetals, 25,26 triple points, 27 and chiral topological insulators. 28 The most studied class of systems, however, is ordered magnetic insulators with topological magnon bands, associated with nonzero Chern numbers. ...
... 40,41 Of particular interest is noncoplanar orders where a finite scalar spin chirality 13 S i · S j × S k can produce the non-trivial topology. 42 This is the reason why several theoretical predictions focus on intrinsically non-coplanar magnetic configurations such as in pyrochlore iridate thin films, 43 and bulk systems, 27 , or noncollinear configurations canted out-of-plane by a magnetic field. For the latter case, the magnon thermal Hall effect has been predicted on the star, 42 honeycomb, 44 and kagome lattices. ...
... The predicted values are on the same or better order as experimental observations for the magnon thermal Hall effect, [14][15][16]18 and predicted values for pyrochlore iridates in the noncollinear allin-all-out spin configuration. 27 We next explore regions of higher canting, where stronger effects are expected. 42,45,58 Recalling the effective field Eq. (15), we achieve this by tuning the applied transverse field, or the in-plane DMI strength. ...
We theoretically study magnetic and topological properties of antiferromagnetic kagome spin systems in the presence of both in- and out-of-plane Dzyaloshinskii-Moriya interactions. In materials such as the iron jarosites, the in-plane interactions stabilize a canted noncollinear "umbrella" magnetic configuration with finite scalar spin chirality. We derive expressions for the canting angle, and use the resulting order as a starting point for a spin-wave analysis. We find topological magnon bands, characterized by non-zero Chern numbers. We calculate the magnon thermal Hall conductivity, and propose the iron jarosites as a promising candidate system for observing the magnon thermal Hall effect in a noncollinear spin configuration. We also show that the thermal conductivity can be tuned by varying an applied magnetic field, or the in-plane Dzyaloshinskii-Moriya strength. In contrast with previous studies of topological magnon bands, the effect is found to be large even in the limit of small canting.
