Competing magnetic phases and fluctuation-driven scalar spin chirality in the kagome metal YMn ₆ Sn ₆

Abstract

Identification, understanding, and manipulation of novel magnetic textures are essential for the discovery of new quantum materials for future spin-based electronic devices. In particular, materials that manifest a large response to external stimuli such as a magnetic field are subject to intense investigation. Here, we study the kagome-net magnet YMn6Sn6 by magnetometry, transport, and neutron diffraction measurements combined with first-principles calculations. We identify a number of nontrivial magnetic phases, explain their microscopic nature, and demonstrate that one of them hosts a large topological Hall effect (THE). We propose a previously unidentified fluctuation-driven mechanism, which leads to the THE at elevated temperatures. This interesting physics comes from parametrically frustrated interplanar exchange interactions that trigger strong magnetic fluctuations. Our results pave a path to chiral spin textures, promising for novel spintronics.

Rare Earth Engineering inRMn6Sn6(R=Ma1, Xu2, Yin3 et al. 2021Phys. Rev. Lett.1193330View full textAdd to dashboardCite

“…Its ρ yx curves also follow the MðHÞ curves [Fig.S5(e)] and we can distinguish ρ AH as the step on the transition. For Tm and Lu, the stable AFM structure[17,18] defies explicit zero-field anomalous effect in their ρ yx , similar as the observation for YMn 6 Sn 6[23,24]. Interestingly, ρ AH in TmMn 6 Sn 6 deviates from the linear MðHÞ above 100 K [Fig.…”

“…This interesting observation supports the critical role of magnetic coupling in the MDF structure. On the other hand, the THE and electronic structure in YMn 6 Sn 6 which has no 4f moments, deserve further elaboration [23][24][25]. Our work highlights the material system which not only largely extends the family of quantum kagome magnets but also intrinsically contains a quantum knob for Chern phase engineering.…”

“…When R is Er and Tm, the Mn and Er=Tm sublattices are independently ordered in an AFM manner because the strength of the magnetic coupling is weak [17,18]. As there is no 4f moment in LuMn 6 Sn 6 , its magnetic structure was reported to be a flat spiral AFM [22], similar to that in YMn 6 Sn 6 [23][24][25].…”

Topological phase transition and charge-spin coupling in the kagome metal YMn6Sn6

“…1(c). The peak persists to 150 K and disappears by 200 K, matching with the FL phase boundary at 170 K 10 . The full temperature range measured for each of the current and applied field configurations is shown in Fig.…”

“…1(a,b). The material orders antiferromagnetically at 340 K and quickly transitions into an incommensurate spiral below 333 K. At all temperatures, a magnetic field applied along the c-axis cants the moments lying in the ab-plane towards the c-axis, while for a magnetic field applied in the ab-plane, a series of competing phases [10][11][12] are formed, as depicted in Fig. 1(c) (see SI2 for details).…”