Topological phase in a two-dimensional metallic heavy-fermion system

Abstract

We report on a topological insulating state in a heavy-fermion system away from half-filling, which is hidden within a ferromagnetic metallic phase. In this phase, the cooperation of the RKKY interaction and the Kondo effect, together with the spin-orbit coupling, induces a spin-selective gap, bringing about topologically non-trivial properties. This topological phase is robust against a change in the chemical potential in a much wider range than the gap size. We analyze these remarkable properties by using dynamical mean field theory and the numerical renormalization group. Its topological properties support a gapless chiral edge mode, which exhibits a non-Tomonaga-Luttinger liquid behavior due to the coupling with bulk ferromagnetic spin fluctuations. We also propose that the effects of the spin fluctuations on the edge mode can be detected via the NMR relaxation time measurement.

Topological Insulator Materials

“…There are already a number of theoretical works to elucidate the effect of electron correlations in TIs. [293][294][295][296][297][298] As the experiments on TIs become refined, the electron correlation physics will gradually be elucidated. Perhaps more importantly, if a material that becomes both insulating and topologically nontrivial because of strong electron correlations is discovered, such a materials would be called a topological Mott insulator 299) and will create an entirely new and rich field of research.…”

Topological Properties of Correlated Insulators in One Dimension

“…These proposals stimulate studies of the correlation effect in the topological phases, which is one of the current important issues. So far, the correlation effects on topological phases have been extensively studied [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] since electron correlations under such nontrivial conditions are expected to produce exotic phenomena. For example, the phase competition between topological phases and long-range ordered phases has been discussed [14][15][16][17][18][19][20][21][22][23], and nontrivial phases induced by Coulomb interactions have been proposed [24][25][26].…”

Correlation effects in pyrochlore iridate thin films grown along the [111] direction

“…17,18 One possible effect of electronic interactions is magnetic order that carries with it a topological phase transition (either from a non-topological system to a topological one, or from a TI to a non-topological magnetically ordered state). [19][20][21][22][23] Among the real-material proposals for systems expected to exhibit topological properties, transition metal oxides (TMO) are a promising candidate for realizing nontrivial interacting topological phases. [24][25][26][27][28][29][30][31][32][33][34][35][36] Among the bulk (as apposed to thin-film) TMO that have been theoretically studied in the context of topological phases, the irradiates have been particularly singled out.…”