Metamagnetic multiband Hall effect and quantum oscillations in a topological magnet
ORAL
Abstract
The Hall effect is a transverse electrical response of an electric current under a magnetic field. In addition to the normal Hall effect arising from the Lorentz force on charge carriers, magnetic materials may exhibit an anomalous Hall effect (AHE) or a topological Hall effect (THE). It is often empirically assumed that the difference between the total Hall response and the extrapolated Hall signal at high magnetic fields indicates the presence of AHE or THE. However, this approach is only valid when the carrier concentration or mobility remains unchanged with the applied magnetic field.
We synthesized and investigated a binary Nd-Al compound. The large, non-saturating magnetoresistance (up to 4500% at 1.9 K, 14 T) and uncompensated carriers suggest that it may host nontrivial band topology in its electronic structure. A pronounced Hall anomaly (as large as 105 Ohm-1 cm-1) was obtained using the empirical approach, while our neutron scattering results indicate that this compound should not exhibit THE. Instead, the Hall effect of this compound can be well explained by a metamagnetic (MM) multiband Hall effect [1], and the carrier concentration and mobility change significantly across the MM transition. This interpretation is further supported by our Shubnikov-de Haas oscillation measurements, which reveal distinct changes in the quantum oscillation frequency and quasiparticle effective mass across the MM transition.
[1] Kurumaji, T., et al. PNAS 121 (23) e2318411121 (2024).
We synthesized and investigated a binary Nd-Al compound. The large, non-saturating magnetoresistance (up to 4500% at 1.9 K, 14 T) and uncompensated carriers suggest that it may host nontrivial band topology in its electronic structure. A pronounced Hall anomaly (as large as 105 Ohm-1 cm-1) was obtained using the empirical approach, while our neutron scattering results indicate that this compound should not exhibit THE. Instead, the Hall effect of this compound can be well explained by a metamagnetic (MM) multiband Hall effect [1], and the carrier concentration and mobility change significantly across the MM transition. This interpretation is further supported by our Shubnikov-de Haas oscillation measurements, which reveal distinct changes in the quantum oscillation frequency and quasiparticle effective mass across the MM transition.
[1] Kurumaji, T., et al. PNAS 121 (23) e2318411121 (2024).
*This work is funded by the Department of Defense, Air Force Office of Scientific Research under Grant No. FA9550-21-1-0343.
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Presenters
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Yuxiang Gao
- Rice University